Add line height setting to views::Label & use it for notifications.

ui/gfx/canvas_skia.cc

Index: ui/gfx/canvas_skia.cc
diff --git a/ui/gfx/canvas_skia.cc b/ui/gfx/canvas_skia.cc
index 2d995cfb8664f7367d398250342e4d9bc55f60b3..3dba2a3a35dbc57beac723a6ddb0a17bceb178e8 100644
--- a/ui/gfx/canvas_skia.cc
+++ b/ui/gfx/canvas_skia.cc
@@ -169,6 +169,7 @@ int AdjustPlatformSpecificFlags(const string16& text, int flags) {
 void Canvas::SizeStringInt(const string16& text,
                            const Font& font,
                            int* width, int* height,
+                           int line_height,
                            int flags) {
   DCHECK_GE(*width, 0);
   DCHECK_GE(*height, 0);
@@ -201,7 +202,7 @@ void Canvas::SizeStringInt(const string16& text,
       render_text->SetText(strings[i]);
       const Size string_size = render_text->GetStringSize();
       w = std::max(w, string_size.width());
-      h += string_size.height();
+      h += (i > 0 && line_height >= 0) ? line_height : string_size.height();

[msw, 2013/04/17 20:12:59]

Should line_height really be ignored if the text isn't multi-line?

[dharcourt, 2013/04/17 23:29:40]

I think so. Changing the line height should change the distance between
baselines of successive lines of text, but not the amount of space above and
below the text as a whole. To make this work the line height must be ignored for
the first or last line of text. This should make text layout more predictable.

For example consider text that needs 9 pixels of padding above it and 8 pixels
of padding below it to get 12 pixels of white space before the top of the first
line's capitals and below the baseline of the last line (because the font
already provides 3 pixels above its capitals and 4 pixels below its baseline).
You should be able to change the line spacing of that text without changing the
amount of padding you need to achieve the 12 pixels of space.

     }
     *width = w;
     *height = h;
@@ -228,6 +229,7 @@ void Canvas::DrawStringWithShadows(const string16& text,
                                    const Font& font,
                                    SkColor color,
                                    const Rect& text_bounds,
+                                   int line_height,
                                    int flags,
                                    const ShadowValues& shadows) {
   if (!IntersectsClipRect(text_bounds))
@@ -268,18 +270,22 @@ void Canvas::DrawStringWithShadows(const string16& text,
     for (size_t i = 0; i < strings.size(); i++) {
       ui::Range range = StripAcceleratorChars(flags, &strings[i]);
       UpdateRenderText(rect, strings[i], font, flags, color, render_text.get());
-      const int line_height = render_text->GetStringSize().height();
+      int line_padding = 0;
+      if (line_height >= 0)
+        line_padding = line_height - render_text->GetStringSize().height();
+      else
+        line_height = render_text->GetStringSize().height();
 
       // TODO(msw|asvitkine): Center Windows multi-line text: crbug.com/107357
 #if !defined(OS_WIN)
       if (i == 0) {
         // TODO(msw|asvitkine): Support multi-line text with varied heights.
-        const int aggregate_height = strings.size() * line_height;
-        rect += Vector2d(0, (text_bounds.height() - aggregate_height) / 2);
+        const int text_height = strings.size() * line_height - line_padding;
+        rect += Vector2d(0, (text_bounds.height() - text_height) / 2);
       }
 #endif
 
-      rect.set_height(line_height);
+      rect.set_height(line_height - line_padding);
 
       if (range.IsValid())
         render_text->ApplyStyle(UNDERLINE, true, range);
@@ -313,10 +319,10 @@ void Canvas::DrawStringWithShadows(const string16& text,
     UpdateRenderText(rect, adjusted_text, font, flags, color,
                      render_text.get());
 
-    const int line_height = render_text->GetStringSize().height();
+    const int text_height = render_text->GetStringSize().height();

[msw, 2013/04/17 20:12:59]

nit: Move this above to use in line_height/line_padding init; then:
const int line_padding = (line_height < 0) ? 0 : text_height - line_height;
(you'd need to rename the other |text_height|, maybe to |total_height|?)

[dharcourt, 2013/04/17 23:29:40]

I don't think I can do that because the line height above is computed on a
per-line basis, with possibly different GetStringSize().height() values returned
for different lines. I can't use this text_height for all lines.

Am I missing something?

     // Center the text vertically.
-    rect += Vector2d(0, (text_bounds.height() - line_height) / 2);
-    rect.set_height(line_height);
+    rect += Vector2d(0, (text_bounds.height() - text_height) / 2);

[msw, 2013/04/17 20:12:59]

Again, Should line_height really be ignored if the text isn't multi-line?

[dharcourt, 2013/04/17 23:29:40]

I think so, as described above.

+    rect.set_height(text_height);
     render_text->SetDisplayRect(rect);
     if (range.IsValid())
       render_text->ApplyStyle(UNDERLINE, true, range);