Expand/Collapse Files and Blob Excerpt while Reviewing/Comparing code (#8924)

* update #8659 fold/unfold code diffs

* add fold button style

* update #8659 implement expand up/down codes (blob excerpt)

* fix golint errors

* fix expand direction

* remove debug message

* update css style for blob exceprt

* fix typo in comment

* update style sheet with less

* update expect diff (add SectionInfo)

* update #8942 accept suggested change (fix typo)

* close reader and check file type before get tail section

* adjust button position and check file type before insert fold button

* move index js to web_src

* merge index.js with master

* generate index.js

* update js coding style

modules/git/blob.go

@@ -6,6 +6,7 @@
 package git
 
 import (
+	"bytes"
 	"encoding/base64"
 	"io"
 	"io/ioutil"
@@ -50,6 +51,28 @@ func (b *Blob) GetBlobContent() (string, error) {
 	return string(buf), nil
 }
 
+// GetBlobLineCount gets line count of lob as raw text
+func (b *Blob) GetBlobLineCount() (int, error) {
+	reader, err := b.DataAsync()
+	if err != nil {
+		return 0, err
+	}
+	defer reader.Close()
+	buf := make([]byte, 32*1024)
+	count := 0
+	lineSep := []byte{'\n'}
+	for {
+		c, err := reader.Read(buf)
+		count += bytes.Count(buf[:c], lineSep)
+		switch {
+		case err == io.EOF:
+			return count, nil
+		case err != nil:
+			return count, err
+		}
+	}
+}
+
 // GetBlobContentBase64 Reads the content of the blob with a base64 encode and returns the encoded string
 func (b *Blob) GetBlobContentBase64() (string, error) {
 	dataRc, err := b.DataAsync()

modules/repofiles/diff_test.go

@@ -55,6 +55,15 @@ func TestGetDiffPreview(t *testing.T) {
 								Type:     4,
 								Content:  "@@ -1,3 +1,4 @@",
 								Comments: nil,
+								SectionInfo: &gitdiff.DiffLineSectionInfo{
+									Path:          "README.md",
+									LastLeftIdx:   0,
+									LastRightIdx:  0,
+									LeftIdx:       1,
+									RightIdx:      1,
+									LeftHunkSize:  3,
+									RightHunkSize: 4,
+								},
 							},
 							{
 								LeftIdx:  1,

public/css/index.css

@@ -898,6 +898,7 @@ tbody.commit-list{vertical-align:baseline}
 .repo-buttons .disabled-repo-button a.button:hover{background:0 0!important;color:rgba(0,0,0,.6)!important;box-shadow:0 0 0 1px rgba(34,36,38,.15) inset!important}
 .repo-buttons .ui.labeled.button>.label{border-left:0!important;margin:0!important}
 .tag-code,.tag-code td{background-color:#f0f0f0!important;border-color:#d3cfcf!important;padding-top:8px;padding-bottom:8px}
+td.blob-excerpt{background-color:#fafafa}
 .issue-keyword{border-bottom:1px dotted #959da5;display:inline-block}
 .file-header{display:flex;justify-content:space-between;align-items:center;padding:8px 12px!important}
 .file-info{display:flex;align-items:center}
@@ -1069,3 +1070,7 @@ tbody.commit-list{vertical-align:baseline}
 .comment-code-cloud button.comment-form-reply{margin:.5em .5em .5em 4.5em}
 .comment-code-cloud form.comment-form-reply{margin:0 0 0 4em}
 .file-comment{font:12px 'SF Mono',Consolas,Menlo,'Liberation Mono',Monaco,'Lucida Console',monospace;color:rgba(0,0,0,.87)}
+.ui.fold-code{margin-right:1em;padding-left:5px;cursor:pointer;width:22px;font-size:12px}
+.ui.fold-code:hover{color:#428bca}
+.ui.blob-excerpt{display:block;line-height:20px;font-size:16px;cursor:pointer}
+.ui.blob-excerpt:hover{color:#428bca}

routers/repo/commit.go

@@ -245,6 +245,7 @@ func Diff(ctx *context.Context) {
 	}
 
 	ctx.Data["CommitID"] = commitID
+	ctx.Data["AfterCommitID"] = commitID
 	ctx.Data["Username"] = userName
 	ctx.Data["Reponame"] = repoName
 

routers/repo/compare.go

@@ -5,21 +5,26 @@
 package repo
 
 import (
+	"bufio"
 	"fmt"
+	"html"
 	"path"
+	"path/filepath"
 	"strings"
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/base"
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/highlight"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/services/gitdiff"
 )
 
 const (
-	tplCompare base.TplName = "repo/diff/compare"
+	tplCompare     base.TplName = "repo/diff/compare"
+	tplBlobExcerpt base.TplName = "repo/diff/blob_excerpt"
 )
 
 // setPathsCompareContext sets context data for source and raw paths
@@ -434,3 +439,109 @@ func CompareDiff(ctx *context.Context) {
 
 	ctx.HTML(200, tplCompare)
 }
+
+// ExcerptBlob render blob excerpt contents
+func ExcerptBlob(ctx *context.Context) {
+	commitID := ctx.Params("sha")
+	lastLeft := ctx.QueryInt("last_left")
+	lastRight := ctx.QueryInt("last_right")
+	idxLeft := ctx.QueryInt("left")
+	idxRight := ctx.QueryInt("right")
+	leftHunkSize := ctx.QueryInt("left_hunk_size")
+	rightHunkSize := ctx.QueryInt("right_hunk_size")
+	anchor := ctx.Query("anchor")
+	direction := ctx.Query("direction")
+	filePath := ctx.Query("path")
+	gitRepo := ctx.Repo.GitRepo
+	chunkSize := gitdiff.BlobExceprtChunkSize
+	commit, err := gitRepo.GetCommit(commitID)
+	if err != nil {
+		ctx.Error(500, "GetCommit")
+		return
+	}
+	section := &gitdiff.DiffSection{
+		Name: filePath,
+	}
+	if direction == "up" && (idxLeft-lastLeft) > chunkSize {
+		idxLeft -= chunkSize
+		idxRight -= chunkSize
+		leftHunkSize += chunkSize
+		rightHunkSize += chunkSize
+		section.Lines, err = getExcerptLines(commit, filePath, idxLeft-1, idxRight-1, chunkSize)
+	} else if direction == "down" && (idxLeft-lastLeft) > chunkSize {
+		section.Lines, err = getExcerptLines(commit, filePath, lastLeft, lastRight, chunkSize)
+		lastLeft += chunkSize
+		lastRight += chunkSize
+	} else {
+		section.Lines, err = getExcerptLines(commit, filePath, lastLeft, lastRight, idxRight-lastRight-1)
+		leftHunkSize = 0
+		rightHunkSize = 0
+		idxLeft = lastLeft
+		idxRight = lastRight
+	}
+	if err != nil {
+		ctx.Error(500, "getExcerptLines")
+		return
+	}
+	if idxRight > lastRight {
+		lineText := " "
+		if rightHunkSize > 0 || leftHunkSize > 0 {
+			lineText = fmt.Sprintf("@@ -%d,%d +%d,%d @@\n", idxLeft, leftHunkSize, idxRight, rightHunkSize)
+		}
+		lineText = html.EscapeString(lineText)
+		lineSection := &gitdiff.DiffLine{
+			Type:    gitdiff.DiffLineSection,
+			Content: lineText,
+			SectionInfo: &gitdiff.DiffLineSectionInfo{
+				Path:          filePath,
+				LastLeftIdx:   lastLeft,
+				LastRightIdx:  lastRight,
+				LeftIdx:       idxLeft,
+				RightIdx:      idxRight,
+				LeftHunkSize:  leftHunkSize,
+				RightHunkSize: rightHunkSize,
+			}}
+		if direction == "up" {
+			section.Lines = append([]*gitdiff.DiffLine{lineSection}, section.Lines...)
+		} else if direction == "down" {
+			section.Lines = append(section.Lines, lineSection)
+		}
+	}
+	ctx.Data["section"] = section
+	ctx.Data["fileName"] = filePath
+	ctx.Data["highlightClass"] = highlight.FileNameToHighlightClass(filepath.Base(filePath))
+	ctx.Data["AfterCommitID"] = commitID
+	ctx.Data["Anchor"] = anchor
+	ctx.HTML(200, tplBlobExcerpt)
+}
+
+func getExcerptLines(commit *git.Commit, filePath string, idxLeft int, idxRight int, chunkSize int) ([]*gitdiff.DiffLine, error) {
+	blob, err := commit.Tree.GetBlobByPath(filePath)
+	if err != nil {
+		return nil, err
+	}
+	reader, err := blob.DataAsync()
+	if err != nil {
+		return nil, err
+	}
+	defer reader.Close()
+	scanner := bufio.NewScanner(reader)
+	var diffLines []*gitdiff.DiffLine
+	for line := 0; line < idxRight+chunkSize; line++ {
+		if ok := scanner.Scan(); !ok {
+			break
+		}
+		if line < idxRight {
+			continue
+		}
+		lineText := scanner.Text()
+		diffLine := &gitdiff.DiffLine{
+			LeftIdx:  idxLeft + (line - idxRight) + 1,
+			RightIdx: line + 1,
+			Type:     gitdiff.DiffLinePlain,
+			Content:  " " + lineText,
+		}
+		diffLines = append(diffLines, diffLine)
+	}
+	return diffLines, nil
+}

routers/repo/pull.go

@@ -552,6 +552,7 @@ func ViewPullFiles(ctx *context.Context) {
 		ctx.Data["Username"] = pull.MustHeadUserName()
 		ctx.Data["Reponame"] = pull.HeadRepo.Name
 	}
+	ctx.Data["AfterCommitID"] = endCommitID
 
 	diff, err := gitdiff.GetDiffRangeWithWhitespaceBehavior(diffRepoPath,
 		startCommitID, endCommitID, setting.Git.MaxGitDiffLines,

routers/routes/routes.go

@@ -864,6 +864,10 @@ func RegisterRoutes(m *macaron.Macaron) {
 			m.Get("", repo.Branches)
 		}, repo.MustBeNotEmpty, context.RepoRef(), reqRepoCodeReader)
 
+		m.Group("/blob_excerpt", func() {
+			m.Get("/:sha", repo.SetEditorconfigIfExists, repo.SetDiffViewStyle, repo.ExcerptBlob)
+		}, repo.MustBeNotEmpty, context.RepoRef(), reqRepoCodeReader)
+
 		m.Group("/pulls/:index", func() {
 			m.Get(".diff", repo.DownloadPullDiff)
 			m.Get(".patch", repo.DownloadPullPatch)

services/gitdiff/gitdiff.go

@@ -13,6 +13,7 @@ import (
 	"html/template"
 	"io"
 	"io/ioutil"
+	"net/url"
 	"os"
 	"os/exec"
 	"regexp"
@@ -56,15 +57,42 @@ const (
 	DiffFileRename
 )
 
+// DiffLineExpandDirection represents the DiffLineSection expand direction
+type DiffLineExpandDirection uint8
+
+// DiffLineExpandDirection possible values.
+const (
+	DiffLineExpandNone DiffLineExpandDirection = iota + 1
+	DiffLineExpandSingle
+	DiffLineExpandUpDown
+	DiffLineExpandUp
+	DiffLineExpandDown
+)
+
 // DiffLine represents a line difference in a DiffSection.
 type DiffLine struct {
-	LeftIdx  int
-	RightIdx int
-	Type     DiffLineType
-	Content  string
-	Comments []*models.Comment
+	LeftIdx     int
+	RightIdx    int
+	Type        DiffLineType
+	Content     string
+	Comments    []*models.Comment
+	SectionInfo *DiffLineSectionInfo
 }
 
+// DiffLineSectionInfo represents diff line section meta data
+type DiffLineSectionInfo struct {
+	Path          string
+	LastLeftIdx   int
+	LastRightIdx  int
+	LeftIdx       int
+	RightIdx      int
+	LeftHunkSize  int
+	RightHunkSize int
+}
+
+// BlobExceprtChunkSize represent max lines of excerpt
+const BlobExceprtChunkSize = 20
+
 // GetType returns the type of a DiffLine.
 func (d *DiffLine) GetType() int {
 	return int(d.Type)
@@ -91,6 +119,71 @@ func (d *DiffLine) GetLineTypeMarker() string {
 	return ""
 }
 
+// GetBlobExcerptQuery builds query string to get blob excerpt
+func (d *DiffLine) GetBlobExcerptQuery() string {
+	query := fmt.Sprintf(
+		"last_left=%d&last_right=%d&"+
+			"left=%d&right=%d&"+
+			"left_hunk_size=%d&right_hunk_size=%d&"+
+			"path=%s",
+		d.SectionInfo.LastLeftIdx, d.SectionInfo.LastRightIdx,
+		d.SectionInfo.LeftIdx, d.SectionInfo.RightIdx,
+		d.SectionInfo.LeftHunkSize, d.SectionInfo.RightHunkSize,
+		url.QueryEscape(d.SectionInfo.Path))
+	return query
+}
+
+// GetExpandDirection gets DiffLineExpandDirection
+func (d *DiffLine) GetExpandDirection() DiffLineExpandDirection {
+	if d.Type != DiffLineSection || d.SectionInfo == nil || d.SectionInfo.RightIdx-d.SectionInfo.LastRightIdx <= 1 {
+		return DiffLineExpandNone
+	}
+	if d.SectionInfo.LastLeftIdx <= 0 && d.SectionInfo.LastRightIdx <= 0 {
+		return DiffLineExpandUp
+	} else if d.SectionInfo.RightIdx-d.SectionInfo.LastRightIdx > BlobExceprtChunkSize && d.SectionInfo.RightHunkSize > 0 {
+		return DiffLineExpandUpDown
+	} else if d.SectionInfo.LeftHunkSize <= 0 && d.SectionInfo.RightHunkSize <= 0 {
+		return DiffLineExpandDown
+	}
+	return DiffLineExpandSingle
+}
+
+func getDiffLineSectionInfo(curFile *DiffFile, line string, lastLeftIdx, lastRightIdx int) *DiffLineSectionInfo {
+	var (
+		leftLine  int
+		leftHunk  int
+		rightLine int
+		righHunk  int
+	)
+	ss := strings.Split(line, "@@")
+	ranges := strings.Split(ss[1][1:], " ")
+	leftRange := strings.Split(ranges[0], ",")
+	leftLine, _ = com.StrTo(leftRange[0][1:]).Int()
+	if len(leftRange) > 1 {
+		leftHunk, _ = com.StrTo(leftRange[1]).Int()
+	}
+	if len(ranges) > 1 {
+		rightRange := strings.Split(ranges[1], ",")
+		rightLine, _ = com.StrTo(rightRange[0]).Int()
+		if len(rightRange) > 1 {
+			righHunk, _ = com.StrTo(rightRange[1]).Int()
+		}
+	} else {
+		log.Warn("Parse line number failed: %v", line)
+		rightLine = leftLine
+		righHunk = leftHunk
+	}
+	return &DiffLineSectionInfo{
+		Path:          curFile.Name,
+		LastLeftIdx:   lastLeftIdx,
+		LastRightIdx:  lastRightIdx,
+		LeftIdx:       leftLine,
+		RightIdx:      rightLine,
+		LeftHunkSize:  leftHunk,
+		RightHunkSize: righHunk,
+	}
+}
+
 // escape a line's content or return <br> needed for copy/paste purposes
 func getLineContent(content string) string {
 	if len(content) > 0 {
@@ -248,6 +341,53 @@ func (diffFile *DiffFile) GetHighlightClass() string {
 	return highlight.FileNameToHighlightClass(diffFile.Name)
 }
 
+// GetTailSection creates a fake DiffLineSection if the last section is not the end of the file
+func (diffFile *DiffFile) GetTailSection(gitRepo *git.Repository, leftCommitID, rightCommitID string) *DiffSection {
+	if diffFile.Type != DiffFileChange || diffFile.IsBin || diffFile.IsLFSFile {
+		return nil
+	}
+	leftCommit, err := gitRepo.GetCommit(leftCommitID)
+	if err != nil {
+		return nil
+	}
+	rightCommit, err := gitRepo.GetCommit(rightCommitID)
+	if err != nil {
+		return nil
+	}
+	lastSection := diffFile.Sections[len(diffFile.Sections)-1]
+	lastLine := lastSection.Lines[len(lastSection.Lines)-1]
+	leftLineCount := getCommitFileLineCount(leftCommit, diffFile.Name)
+	rightLineCount := getCommitFileLineCount(rightCommit, diffFile.Name)
+	if leftLineCount <= lastLine.LeftIdx || rightLineCount <= lastLine.RightIdx {
+		return nil
+	}
+	tailDiffLine := &DiffLine{
+		Type:    DiffLineSection,
+		Content: " ",
+		SectionInfo: &DiffLineSectionInfo{
+			Path:         diffFile.Name,
+			LastLeftIdx:  lastLine.LeftIdx,
+			LastRightIdx: lastLine.RightIdx,
+			LeftIdx:      leftLineCount,
+			RightIdx:     rightLineCount,
+		}}
+	tailSection := &DiffSection{Lines: []*DiffLine{tailDiffLine}}
+	return tailSection
+
+}
+
+func getCommitFileLineCount(commit *git.Commit, filePath string) int {
+	blob, err := commit.GetBlobByPath(filePath)
+	if err != nil {
+		return 0
+	}
+	lineCount, err := blob.GetBlobLineCount()
+	if err != nil {
+		return 0
+	}
+	return lineCount
+}
+
 // Diff represents a difference between two git trees.
 type Diff struct {
 	TotalAddition, TotalDeletion int
@@ -510,19 +650,16 @@ func ParsePatch(maxLines, maxLineCharacters, maxFiles int, reader io.Reader) (*D
 		case line[0] == '@':
 			curSection = &DiffSection{}
 			curFile.Sections = append(curFile.Sections, curSection)
-			ss := strings.Split(line, "@@")
-			diffLine := &DiffLine{Type: DiffLineSection, Content: line}
-			curSection.Lines = append(curSection.Lines, diffLine)
-
-			// Parse line number.
-			ranges := strings.Split(ss[1][1:], " ")
-			leftLine, _ = com.StrTo(strings.Split(ranges[0], ",")[0][1:]).Int()
-			if len(ranges) > 1 {
-				rightLine, _ = com.StrTo(strings.Split(ranges[1], ",")[0]).Int()
-			} else {
-				log.Warn("Parse line number failed: %v", line)
-				rightLine = leftLine
+			lineSectionInfo := getDiffLineSectionInfo(curFile, line, leftLine-1, rightLine-1)
+			diffLine := &DiffLine{
+				Type:        DiffLineSection,
+				Content:     line,
+				SectionInfo: lineSectionInfo,
 			}
+			curSection.Lines = append(curSection.Lines, diffLine)
+			// update line number.
+			leftLine = lineSectionInfo.LeftIdx
+			rightLine = lineSectionInfo.RightIdx
 			continue
 		case line[0] == '+':
 			curFile.Addition++
@@ -599,6 +736,8 @@ func ParsePatch(maxLines, maxLineCharacters, maxFiles int, reader io.Reader) (*D
 				break
 			}
 			curFileLinesCount = 0
+			leftLine = 1
+			rightLine = 1
 			curFileLFSPrefix = false
 
 			// Check file diff type and is submodule.
@@ -701,6 +840,7 @@ func GetDiffRangeWithWhitespaceBehavior(repoPath, beforeCommitID, afterCommitID
 		diffArgs = append(diffArgs, actualBeforeCommitID)
 		diffArgs = append(diffArgs, afterCommitID)
 		cmd = exec.Command(git.GitExecutable, diffArgs...)
+		beforeCommitID = actualBeforeCommitID
 	}
 	cmd.Dir = repoPath
 	cmd.Stderr = os.Stderr
@@ -721,6 +861,12 @@ func GetDiffRangeWithWhitespaceBehavior(repoPath, beforeCommitID, afterCommitID
 	if err != nil {
 		return nil, fmt.Errorf("ParsePatch: %v", err)
 	}
+	for _, diffFile := range diff.Files {
+		tailSection := diffFile.GetTailSection(gitRepo, beforeCommitID, afterCommitID)
+		if tailSection != nil {
+			diffFile.Sections = append(diffFile.Sections, tailSection)
+		}
+	}
 
 	if err = cmd.Wait(); err != nil {
 		return nil, fmt.Errorf("Wait: %v", err)

templates/repo/diff/blob_excerpt.tmpl

@@ -0,0 +1,50 @@
+{{if $.IsSplitStyle}}
+  {{range $k, $line := $.section.Lines}}
+  <tr class="{{DiffLineTypeToStr .GetType}}-code nl-{{$k}} ol-{{$k}}">
+    {{if eq .GetType 4}}
+    <td class="lines-num lines-num-old" data-line-num="{{if $line.LeftIdx}}{{$line.LeftIdx}}{{end}}">
+      {{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 5) }}
+      <i class="ui blob-excerpt fa fa-caret-down" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=split&direction=down" data-anchor="{{$.Anchor}}"></i>
+      {{end}}
+      {{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 4) }}
+      <i class="ui blob-excerpt fa fa-caret-up" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=split&direction=up" data-anchor="{{$.Anchor}}"></i>
+      {{end}}
+      {{if or (eq $line.GetExpandDirection 2)}}
+      <i class="ui blob-excerpt octicon octicon-fold" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=split&direction=" data-anchor="{{$.Anchor}}"></i>
+      {{end}}
+    </td>
+    <td colspan="5" class="lines-code lines-code-old "><span class="mono wrap{{if $.highlightClass}} language-{{$.highlightClass}}{{else}} nohighlight{{end}}">{{$.section.GetComputedInlineDiffFor $line}}</span></td>
+    {{else}}
+    <td class="lines-num lines-num-old" data-line-num="{{if $line.LeftIdx}}{{$line.LeftIdx}}{{end}}"><span rel="{{if $line.LeftIdx}}diff-{{Sha1 $.fileName}}L{{$line.LeftIdx}}{{end}}"></span></td>
+    <td class="blob-excerpt lines-type-marker lines-type-marker-old">{{if $line.LeftIdx}}<span class="mono" data-type-marker=""></span>{{end}}</td>
+    <td class="blob-excerpt lines-code lines-code-old halfwidth"><span class="mono wrap{{if $.highlightClass}} language-{{$.highlightClass}}{{else}} nohighlight{{end}}">{{if $line.LeftIdx}}{{$.section.GetComputedInlineDiffFor $line}}{{end}}</span></td>
+    <td class="lines-num lines-num-new" data-line-num="{{if $line.RightIdx}}{{$line.RightIdx}}{{end}}"><span rel="{{if $line.RightIdx}}diff-{{Sha1 $.fileName}}R{{$line.RightIdx}}{{end}}"></span></td>
+    <td class="blob-excerpt lines-type-marker lines-type-marker-new">{{if $line.RightIdx}}<span class="mono" data-type-marker=""></span>{{end}}</td>
+    <td class="blob-excerpt lines-code lines-code-new halfwidth"><span class="mono wrap{{if $.highlightClass}} language-{{$.highlightClass}}{{else}} nohighlight{{end}}">{{if $line.RightIdx}}{{$.section.GetComputedInlineDiffFor $line}}{{end}}</span></td>
+    {{end}}
+  </tr>
+  {{end}}
+{{else}}
+  {{range $k, $line := $.section.Lines}}
+  <tr class="{{DiffLineTypeToStr .GetType}}-code nl-{{$k}} ol-{{$k}}">
+    {{if eq .GetType 4}}
+    <td colspan="2" class="lines-num">
+      {{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 4) }}
+      <i class="ui blob-excerpt fa fa-caret-up" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=unified&direction=up" data-anchor="{{$.Anchor}}"></i>
+      {{end}}
+      {{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 5) }}
+      <i class="ui blob-excerpt fa fa-caret-down" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=unified&direction=down" data-anchor="{{$.Anchor}}"></i>
+      {{end}}
+      {{if or (eq $line.GetExpandDirection 2)}}
+      <i class="ui blob-excerpt octicon octicon-fold" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=unified&direction=" data-anchor="{{$.Anchor}}"></i>
+      {{end}}
+    </td>
+    {{else}}
+    <td class="lines-num lines-num-old" data-line-num="{{if $line.LeftIdx}}{{$line.LeftIdx}}{{end}}"><span rel="{{if $line.LeftIdx}}diff-{{Sha1 $.fileName}}L{{$line.LeftIdx}}{{end}}"></span></td>
+    <td class="lines-num lines-num-new" data-line-num="{{if $line.RightIdx}}{{$line.RightIdx}}{{end}}"><span rel="{{if $line.RightIdx}}diff-{{Sha1 $.fileName}}R{{$line.RightIdx}}{{end}}"></span></td>
+    {{end}}
+    <td class="blob-excerpt lines-type-marker"><span class="mono" data-type-marker="{{$line.GetLineTypeMarker}}"></span></td>
+    <td class="blob-excerpt lines-code{{if (not $line.RightIdx)}} lines-code-old{{end}}"><span class="mono wrap{{if $.highlightClass}} language-{{$.highlightClass}}{{else}} nohighlight{{end}}">{{$.section.GetComputedInlineDiffFor $line}}</span></td>
+  </tr>
+  {{end}}
+{{end}}

templates/repo/diff/box.tmpl

@@ -81,6 +81,15 @@
 			{{else}}
 				<div class="diff-file-box diff-box file-content {{TabSizeClass $.Editorconfig $file.Name}}" id="diff-{{.Index}}">
 					<h4 class="ui top attached normal header">
+						{{$isImage := false}}
+						{{if $file.IsDeleted}}
+							{{$isImage = (call $.IsImageFileInBase $file.Name)}}
+						{{else}}
+							{{$isImage = (call $.IsImageFileInHead $file.Name)}}
+						{{end}}
+						{{if or (not $file.IsBin) $isImage}}
+						<i class="ui fold-code grey fa fa-chevron-down"></i>
+						{{end}}
 						<div class="diff-counter count">
 							{{if $file.IsBin}}
 								{{$.i18n.Tr "repo.diff.bin"}}
@@ -104,12 +113,6 @@
 					</h4>
 					<div class="ui attached unstackable table segment">
 						{{if ne $file.Type 4}}
-							{{$isImage := false}}
-							{{if $file.IsDeleted}}
-								{{$isImage = (call $.IsImageFileInBase $file.Name)}}
-							{{else}}
-								{{$isImage = (call $.IsImageFileInHead $file.Name)}}
-							{{end}}
 							<div class="file-body file-code code-view code-diff {{if $.IsSplitStyle}}code-diff-split{{else}}code-diff-unified{{end}}">
 								<table>
 									<tbody>
@@ -121,12 +124,27 @@
 												{{range $j, $section := $file.Sections}}
 													{{range $k, $line := $section.Lines}}
 														<tr class="{{DiffLineTypeToStr .GetType}}-code nl-{{$k}} ol-{{$k}}">
-															<td class="lines-num lines-num-old" data-line-num="{{if $line.LeftIdx}}{{$line.LeftIdx}}{{end}}"><span rel="{{if $line.LeftIdx}}diff-{{Sha1 $file.Name}}L{{$line.LeftIdx}}{{end}}"></span></td>
-															<td class="lines-type-marker lines-type-marker-old">{{if $line.LeftIdx}}<span class="mono" data-type-marker="{{$line.GetLineTypeMarker}}"></span>{{end}}</td>
-															<td class="lines-code lines-code-old halfwidth">{{if and $.SignedUserID $line.CanComment $.PageIsPullFiles (not (eq .GetType 2))}}<a class="ui green button add-code-comment add-code-comment-left" data-path="{{$file.Name}}" data-side="left" data-idx="{{$line.LeftIdx}}">+</a>{{end}}<span class="mono wrap{{if $highlightClass}} language-{{$highlightClass}}{{else}} nohighlight{{end}}">{{if $line.LeftIdx}}{{$section.GetComputedInlineDiffFor $line}}{{end}}</span></td>
-															<td class="lines-num lines-num-new" data-line-num="{{if $line.RightIdx}}{{$line.RightIdx}}{{end}}"><span rel="{{if $line.RightIdx}}diff-{{Sha1 $file.Name}}R{{$line.RightIdx}}{{end}}"></span></td>
-															<td class="lines-type-marker lines-type-marker-new">{{if $line.RightIdx}}<span class="mono" data-type-marker="{{$line.GetLineTypeMarker}}"></span>{{end}}</td>
-															<td class="lines-code lines-code-new halfwidth">{{if and $.SignedUserID $line.CanComment $.PageIsPullFiles (not (eq .GetType 3))}}<a class="ui green button add-code-comment add-code-comment-right" data-path="{{$file.Name}}" data-side="right" data-idx="{{$line.RightIdx}}">+</a>{{end}}<span class="mono wrap{{if $highlightClass}} language-{{$highlightClass}}{{else}} nohighlight{{end}}">{{if $line.RightIdx}}{{$section.GetComputedInlineDiffFor $line}}{{end}}</span></td>
+															{{if eq .GetType 4}}
+																<td class="lines-num lines-num-old">
+																	{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 5) }}
+																		<i class="ui blob-excerpt fa fa-caret-down" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=split&direction=down" data-anchor="diff-{{Sha1 $file.Name}}K{{$line.SectionInfo.RightIdx}}"></i>
+																	{{end}}
+																	{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 4) }}
+																		<i class="ui blob-excerpt fa fa-caret-up" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=split&direction=up" data-anchor="diff-{{Sha1 $file.Name}}K{{$line.SectionInfo.RightIdx}}"></i>
+																	{{end}}
+																	{{if or (eq $line.GetExpandDirection 2)}}
+																		<i class="ui blob-excerpt octicon octicon-fold" data-url="{{$.RepoLink}}/blob_excerpt/{{$.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=split&direction=" data-anchor="diff-{{Sha1 $file.Name}}K{{$line.SectionInfo.RightIdx}}"></i>
+																	{{end}}
+																</td>
+																<td colspan="5" class="lines-code lines-code-old "><span class="mono wrap{{if $highlightClass}} language-{{$highlightClass}}{{else}} nohighlight{{end}}">{{$section.GetComputedInlineDiffFor $line}}</span></td>
+															{{else}}
+																<td class="lines-num lines-num-old" data-line-num="{{if $line.LeftIdx}}{{$line.LeftIdx}}{{end}}"><span rel="{{if $line.LeftIdx}}diff-{{Sha1 $file.Name}}L{{$line.LeftIdx}}{{end}}"></span></td>
+																<td class="lines-type-marker lines-type-marker-old">{{if $line.LeftIdx}}<span class="mono" data-type-marker="{{$line.GetLineTypeMarker}}"></span>{{end}}</td>
+																<td class="lines-code lines-code-old halfwidth">{{if and $.SignedUserID $line.CanComment $.PageIsPullFiles (not (eq .GetType 2))}}<a class="ui green button add-code-comment add-code-comment-left" data-path="{{$file.Name}}" data-side="left" data-idx="{{$line.LeftIdx}}">+</a>{{end}}<span class="mono wrap{{if $highlightClass}} language-{{$highlightClass}}{{else}} nohighlight{{end}}">{{if $line.LeftIdx}}{{$section.GetComputedInlineDiffFor $line}}{{end}}</span></td>
+																<td class="lines-num lines-num-new" data-line-num="{{if $line.RightIdx}}{{$line.RightIdx}}{{end}}"><span rel="{{if $line.RightIdx}}diff-{{Sha1 $file.Name}}R{{$line.RightIdx}}{{end}}"></span></td>
+																<td class="lines-type-marker lines-type-marker-new">{{if $line.RightIdx}}<span class="mono" data-type-marker="{{$line.GetLineTypeMarker}}"></span>{{end}}</td>
+																<td class="lines-code lines-code-new halfwidth">{{if and $.SignedUserID $line.CanComment $.PageIsPullFiles (not (eq .GetType 3))}}<a class="ui green button add-code-comment add-code-comment-right" data-path="{{$file.Name}}" data-side="right" data-idx="{{$line.RightIdx}}">+</a>{{end}}<span class="mono wrap{{if $highlightClass}} language-{{$highlightClass}}{{else}} nohighlight{{end}}">{{if $line.RightIdx}}{{$section.GetComputedInlineDiffFor $line}}{{end}}</span></td>
+															{{end}}
 														</tr>
 														{{if gt (len $line.Comments) 0}}
 															<tr class="add-code-comment">

templates/repo/diff/section_unified.tmpl

@@ -4,9 +4,17 @@
 	{{range $k, $line := $section.Lines}}
 		<tr class="{{DiffLineTypeToStr .GetType}}-code nl-{{$k}} ol-{{$k}}">
 			{{if eq .GetType 4}}
-			<td colspan="2" class="lines-num">
-				{{/* {{if gt $j 0}}<span class="fold octicon octicon-fold"></span>{{end}} */}}
-			</td>
+				<td colspan="2" class="lines-num">
+				{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 5) }}
+					<i class="ui blob-excerpt fa fa-caret-down" data-url="{{$.root.RepoLink}}/blob_excerpt/{{$.root.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=unified&direction=down" data-anchor="diff-{{Sha1 $file.Name}}K{{$line.SectionInfo.RightIdx}}"></i>
+				{{end}}
+				{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 4) }}
+					<i class="ui blob-excerpt fa fa-caret-up" data-url="{{$.root.RepoLink}}/blob_excerpt/{{$.root.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=unified&direction=up" data-anchor="diff-{{Sha1 $file.Name}}K{{$line.SectionInfo.RightIdx}}"></i>
+				{{end}}
+				{{if or (eq $line.GetExpandDirection 2)}}
+					<i class="ui blob-excerpt octicon octicon-fold" data-url="{{$.root.RepoLink}}/blob_excerpt/{{$.root.AfterCommitID}}" data-query="{{$line.GetBlobExcerptQuery}}&style=unified&direction=" data-anchor="diff-{{Sha1 $file.Name}}K{{$line.SectionInfo.RightIdx}}"></i>
+				{{end}}
+				</td>
 			{{else}}
 			<td class="lines-num lines-num-old" data-line-num="{{if $line.LeftIdx}}{{$line.LeftIdx}}{{end}}"><span rel="{{if $line.LeftIdx}}diff-{{Sha1 $file.Name}}L{{$line.LeftIdx}}{{end}}"></span></td>
 			<td class="lines-num lines-num-new" data-line-num="{{if $line.RightIdx}}{{$line.RightIdx}}{{end}}"><span rel="{{if $line.RightIdx}}diff-{{Sha1 $file.Name}}R{{$line.RightIdx}}{{end}}"></span></td>

web_src/js/index.js

@@ -1852,6 +1852,27 @@ function initCodeView() {
       }
     }).trigger('hashchange');
   }
+  $('.ui.fold-code').on('click', (e) => {
+    const $foldButton = $(e.target);
+    if ($foldButton.hasClass('fa-chevron-down')) {
+      $(e.target).parent().next().slideUp('fast', () => {
+        $foldButton.removeClass('fa-chevron-down').addClass('fa-chevron-right');
+      });
+    } else {
+      $(e.target).parent().next().slideDown('fast', () => {
+        $foldButton.removeClass('fa-chevron-right').addClass('fa-chevron-down');
+      });
+    }
+  });
+  function insertBlobExcerpt(e) {
+    const $blob = $(e.target);
+    const $row = $blob.parent().parent();
+    $.get(`${$blob.data('url')}?${$blob.data('query')}&anchor=${$blob.data('anchor')}`, (blob) => {
+      $row.replaceWith(blob);
+      $(`[data-anchor="${$blob.data('anchor')}"]`).on('click', (e) => { insertBlobExcerpt(e); });
+    });
+  }
+  $('.ui.blob-excerpt').on('click', (e) => { insertBlobExcerpt(e); });
 }
 
 function initU2FAuth() {

web_src/less/_repository.less

@@ -2438,6 +2438,10 @@ tbody.commit-list {
     padding-bottom: 8px;
 }
 
+td.blob-excerpt {
+    background-color: #fafafa;
+}
+
 .issue-keyword {
     border-bottom: 1px dotted #959da5;
     display: inline-block;

web_src/less/_review.less

@@ -108,3 +108,26 @@
     font: 12px @monospaced-fonts, monospace;
     color: rgba(0, 0, 0, 0.87);
 }
+
+.ui.fold-code {
+    margin-right: 1em;
+    padding-left: 5px;
+    cursor: pointer;
+    width: 22px;
+    font-size: 12px;
+}
+
+.ui.fold-code:hover {
+    color: #428bca;
+}
+
+.ui.blob-excerpt {
+    display: block;
+    line-height: 20px;
+    font-size: 16px;
+    cursor: pointer;
+}
+
+.ui.blob-excerpt:hover {
+    color: #428bca;
+}