Change verticalScrollbar's height according to block decorations

spec/text-editor-presenter-spec.coffee

@@ -486,6 +486,39 @@ describe "TextEditorPresenter", ->
           presenter = buildPresenter(scrollTop: 0, lineHeight: 10, explicitHeight: 500)
           expect(presenter.getState().verticalScrollbar.scrollHeight).toBe 500
 
+        it "updates when new block decorations are measured, changed or destroyed", ->
+          presenter = buildPresenter(scrollTop: 0, lineHeight: 10)
+          expect(presenter.getState().verticalScrollbar.scrollHeight).toBe editor.getScreenLineCount() * 10
+
+          addBlockDecorationAtScreenRow = (screenRow) ->
+            editor.decorateMarker(
+              editor.markScreenPosition([screenRow, 0], invalidate: "never"),
+              type: "block",
+              item: document.createElement("div")
+            )
+
+          blockDecoration1 = addBlockDecorationAtScreenRow(0)
+          blockDecoration2 = addBlockDecorationAtScreenRow(3)
+          blockDecoration3 = addBlockDecorationAtScreenRow(7)
+
+          presenter.setBlockDecorationSize(blockDecoration1, 0, 35.8)
+          presenter.setBlockDecorationSize(blockDecoration2, 0, 50.3)
+          presenter.setBlockDecorationSize(blockDecoration3, 0, 95.2)
+
+          linesHeight = editor.getScreenLineCount() * 10
+          blockDecorationsHeight = Math.round(35.8 + 50.3 + 95.2)
+          expect(presenter.getState().verticalScrollbar.scrollHeight).toBe(linesHeight + blockDecorationsHeight)
+
+          presenter.setBlockDecorationSize(blockDecoration2, 0, 100.3)
+
+          blockDecorationsHeight = Math.round(35.8 + 100.3 + 95.2)
+          expect(presenter.getState().verticalScrollbar.scrollHeight).toBe(linesHeight + blockDecorationsHeight)
+
+          waitsForStateToUpdate presenter, -> blockDecoration3.destroy()
+          runs ->
+            blockDecorationsHeight = Math.round(35.8 + 100.3)
+            expect(presenter.getState().verticalScrollbar.scrollHeight).toBe(linesHeight + blockDecorationsHeight)
+
         it "updates when the ::lineHeight changes", ->
           presenter = buildPresenter(scrollTop: 0, lineHeight: 10)
           expectStateUpdate presenter, -> presenter.setLineHeight(20)

src/text-editor-presenter.coffee

@@ -28,6 +28,7 @@ class TextEditorPresenter
     @lineDecorationsByScreenRow = {}
     @lineNumberDecorationsByScreenRow = {}
     @customGutterDecorationsByGutterName = {}
+    @blockDecorationsDimensions = new Map
     @screenRowsToMeasure = []
     @transferMeasurementsToModel()
     @transferMeasurementsFromModel()
@@ -71,6 +72,7 @@ class TextEditorPresenter
   getPreMeasurementState: ->
     @updating = true
 
+    @updateBlockDecorations() if @shouldUpdateBlockDecorations
     @updateVerticalDimensions()
     @updateScrollbarDimensions()
 
@@ -140,6 +142,7 @@ class TextEditorPresenter
     @shouldUpdateHiddenInputState = false
     @shouldUpdateContentState = false
     @shouldUpdateDecorations = false
+    @shouldUpdateBlockDecorations = false
     @shouldUpdateLinesState = false
     @shouldUpdateTilesState = false
     @shouldUpdateCursorsState = false
@@ -158,6 +161,7 @@ class TextEditorPresenter
     @shouldUpdateHiddenInputState = true
     @shouldUpdateContentState = true
     @shouldUpdateDecorations = true
+    @shouldUpdateBlockDecorations = true
     @shouldUpdateLinesState = true
     @shouldUpdateTilesState = true
     @shouldUpdateCursorsState = true
@@ -188,6 +192,8 @@ class TextEditorPresenter
       @shouldUpdateLineNumbersState = true
       @shouldUpdateDecorations = true
       @shouldUpdateOverlaysState = true
+      @shouldUpdateBlockDecorations = true
+      @shouldUpdateVerticalScrollState = true
       @shouldUpdateCustomGutterDecorationState = true
       @emitDidUpdateState()
 
@@ -727,10 +733,19 @@ class TextEditorPresenter
       @scrollHeight = scrollHeight
       @updateScrollTop(@scrollTop)
 
+  getLinesHeight: ->
+    @lineHeight * @model.getScreenLineCount()
+
+  getBlockDecorationsHeight: ->
+    sizes = Array.from(@blockDecorationsDimensions.values())
+    sum = (a, b) -> a + b
+    height = sizes.map((size) -> size.height).reduce(sum, 0)
+    height
+
   updateVerticalDimensions: ->
     if @lineHeight?
       oldContentHeight = @contentHeight
-      @contentHeight = @lineHeight * @model.getScreenLineCount()
+      @contentHeight = Math.round(@getLinesHeight() + @getBlockDecorationsHeight())
 
     if @contentHeight isnt oldContentHeight
       @updateHeight()
@@ -1364,6 +1379,24 @@ class TextEditorPresenter
 
       @emitDidUpdateState()
 
+  setBlockDecorationSize: (decoration, width, height) ->
+    @blockDecorationsDimensions.set(decoration.id, {width, height})
+
+    @shouldUpdateBlockDecorations = true
+    @shouldUpdateVerticalScrollState = true
+    @emitDidUpdateState()
+
+  updateBlockDecorations: ->
+    blockDecorations = {}
+    for decoration in @model.getDecorations(type: "block")
+      blockDecorations[decoration.id] = decoration
+
+    @blockDecorationsDimensions.forEach (value, key) =>
+      unless blockDecorations.hasOwnProperty(key)
+        @blockDecorationsDimensions.delete(key)
+
+    @shouldUpdateVerticalScrollState = true
+
   observeCursor: (cursor) ->
     didChangePositionDisposable = cursor.onDidChangePosition =>
       @shouldUpdateHiddenInputState = true if cursor.isLastCursor()