Draw text via Skia in RenderTextLinux.

ui/gfx/render_text_linux.cc

Index: ui/gfx/render_text_linux.cc
===================================================================
--- ui/gfx/render_text_linux.cc	(revision 113213)
+++ ui/gfx/render_text_linux.cc	(working copy)
@@ -6,10 +6,12 @@
 
 #include <pango/pangocairo.h>
 #include <algorithm>
+#include <vector>
 
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
 #include "ui/gfx/canvas_skia.h"
+#include "ui/gfx/font.h"
 #include "ui/gfx/pango_util.h"
 #include "unicode/uchar.h"
 #include "unicode/ustring.h"
@@ -260,27 +262,104 @@
 }
 
 void RenderTextLinux::DrawVisualText(Canvas* canvas) {
-  Rect bounds(display_rect());
+  DCHECK(layout_);
 
-  // Clip the canvas to the text display area.
-  SkCanvas* canvas_skia = canvas->GetSkCanvas();
+  Point offset(GetVisualOrigin());
+  SkScalar x = SkIntToScalar(offset.x());
+  SkScalar y = SkIntToScalar(offset.y());
 
-  skia::ScopedPlatformPaint scoped_platform_paint(canvas_skia);
-  cairo_t* cr = scoped_platform_paint.GetPlatformSurface();
-  cairo_save(cr);
-  cairo_rectangle(cr, bounds.x(), bounds.y(), bounds.width(), bounds.height());
-  cairo_clip(cr);
 
-  int text_width, text_height;
-  pango_layout_get_pixel_size(layout_, &text_width, &text_height);
-  Point offset(ToViewPoint(Point()));
-  // Vertically centered.
-  int text_y = offset.y() + ((bounds.height() - text_height) / 2);
-  // TODO(xji): need to use SkCanvas->drawPosText() for gpu acceleration.
-  cairo_move_to(cr, offset.x(), text_y);
-  pango_cairo_show_layout(cr, layout_);
+  std::vector<SkPoint> pos;
+  std::vector<uint16> glyphs;
 
-  cairo_restore(cr);
+  StyleRanges styles(style_ranges());
+  ApplyCompositionAndSelectionStyles(&styles);
+
+  // Pre-calculate UTF16 indeces style ranges to UTF16 indices.

[xji, 2011/12/07 00:56:51]

to *UTF8* indices.

[Alexei Svitkine (slow), 2011/12/07 16:11:21]

Done.

+  // TODO(asvitkine): Can we cache these?
+  std::vector<ui::Range> style_ranges_utf8;
+  style_ranges_utf8.reserve(styles.size());
+  size_t start_index = 0;
+  for (size_t i = 0; i < styles.size(); ++i) {
+    size_t end_index = Utf16IndexToUtf8Index(styles[i].range.end());
+    style_ranges_utf8.push_back(ui::Range(start_index, end_index));
+    start_index = end_index;
+  }
+
+  bool is_rtl = (GetTextDirection() == base::i18n::RIGHT_TO_LEFT);

[xji, 2011/12/07 00:56:51]

this should be run's directionality, not text's.

[Alexei Svitkine (slow), 2011/12/07 16:11:21]

Done. I've also added a helper function IsRunLTR() to avoid repeating the
obscure way to get this from Pango.

+  size_t style_increment = (is_rtl ? -1 : 1);
+
+  internal::SkiaTextRenderer renderer(canvas);
+  for (GSList* it = current_line_->runs; it; it = it->next) {
+    PangoLayoutRun* run = reinterpret_cast<PangoLayoutRun*>(it->data);
+    size_t run_start = run->item->offset;
+    size_t run_end = run_start + run->item->length;
+
+    // Find the initial style for this run.
+    // TODO(asvitkine): Can we avoid looping here, e.g. by caching this per run?
+    int style;
+    if (is_rtl) {

[xji, 2011/12/07 00:56:51]

sorry for the confusion.
I mean the style initialization should be based on a *run*'s directionality, not
the whole text's directionality.

you probably do not need to use the whole text's 'is_rtl' to guide searching
from end to start or start to end. It probably does not have performance gain,
and the code looks more complicated.

[Alexei Svitkine (slow), 2011/12/07 16:11:21]

That version of the code was structured in a way that needed the two loops to be
correct. You're right that it's too complex for dubious gain, so I've rewritten
in a way that works for both cases.

+      style = style_ranges_utf8.size() - 1;
+      int prev = style - 1;
+      while (prev >= 0 && style_ranges_utf8[prev].end() >= run_end)
+        style = prev--;
+    } else {
+      style = 0;
+      size_t next = style + 1;
+      while (next < styles.size() &&
+             style_ranges_utf8[next].start() <= run_start) {
+        style = next++;
+      }
+    }
+
+    int glyph_count = run->glyphs->num_glyphs;
+    glyphs.resize(glyph_count);
+    pos.resize(glyph_count);
+
+    PangoFontDescription* native_font =
+        pango_font_describe(run->item->analysis.font);
+    renderer.SetFont(gfx::Font(native_font));
+    pango_font_description_free(native_font);
+
+    SkScalar glyph_x = x;
+    SkScalar start_x = x;
+    int start = 0;
+    for (int i = 0; i < glyph_count; ++i) {
+      const PangoGlyphInfo& glyph = run->glyphs->glyphs[i];
+      glyphs[i] = static_cast<uint16>(glyph.glyph);
+      pos[i].set(glyph_x + PANGO_PIXELS(glyph.geometry.x_offset),
+                 y + PANGO_PIXELS(glyph.geometry.y_offset));
+      glyph_x += PANGO_PIXELS(glyph.geometry.width);
+
+      // If this glyph is beyond the current style, draw the glyphs so far and
+      // advance to the next style.
+      size_t glyph_byte_index = run_start + run->glyphs->log_clusters[i];
+      if (!style_ranges_utf8[style].Contains(ui::Range(glyph_byte_index))) {

[xji, 2011/12/07 00:56:51]

isn't style_range's end exclusive? Then Contains() returns true if
glyph_byte_index == style_range_utf8[style].end, which is not correct for this
purpose.

[Alexei Svitkine (slow), 2011/12/07 16:11:21]

You're right! Fixed.

+        renderer.SetForegroundColor(styles[style].foreground);
+        renderer.DrawPosText(&pos[start], &glyphs[start], i - start);
+        if (styles[style].underline || styles[style].strike) {
+          renderer.DrawDecorations(start_x, y, glyph_x - start_x,
+                                   styles[style].underline,
+                                   styles[style].strike);
+        }
+
+        style += style_increment;
+        start = i;
+        start_x = glyph_x;
+      }
+    }
+
+    // Draw the remaining glyphs.
+    renderer.SetForegroundColor(styles[style].foreground);
+    renderer.DrawPosText(&pos[start], &glyphs[start], glyph_count - start);
+    if (styles[style].underline || styles[style].strike) {
+       renderer.DrawDecorations(start_x, y, glyph_x - start_x,
+                                styles[style].underline,
+                                styles[style].strike);
+    }
+
+    x = glyph_x;
+  }
 }
 
 size_t RenderTextLinux::IndexOfAdjacentGrapheme(size_t index, bool next) {