Fixes two Linux canvas related bugs.

. The platform paint was allocating at a size bigger than necessary.
. ChromeCanvas::DrawStringInt was not taking into account the matrix on
  the canvas, which means the text could be drawn at the wrong
  location.

BUG=none
TEST=none


Review URL: http://codereview.chromium.org/99279

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@15205 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 33 insertions, 7 deletions

diff --git a/chrome/common/gfx/chrome_canvas.h b/chrome/common/gfx/chrome_canvas.h
index a16f9da..72db8a5 100644
--- a/chrome/common/gfx/chrome_canvas.h
+++ b/chrome/common/gfx/chrome_canvas.h
@@ -19,6 +19,10 @@ namespace gfx {
 class Rect;
 }
 
+#if defined(OS_LINUX)
+typedef struct _cairo cairo_t;
+#endif
+
 // ChromeCanvas is the SkCanvas used by Views for all painting. It
 // provides a handful of methods for the common operations used throughout
 // Views. With few exceptions, you should NOT create a ChromeCanvas directly,
@@ -179,6 +183,13 @@ class ChromeCanvas : public skia::PlatformCanvas {
   // Extracts a bitmap from the contents of this canvas.
   SkBitmap ExtractBitmap();
 
+#if defined(OS_LINUX)
+  // Applies current matrix on the canvas to the cairo context. This should be
+  // invoked anytime you plan on drawing directly to the cairo context. Be
+  // sure and set the matrix back to the identity when done.
+  void ApplySkiaMatrixToCairoContext(cairo_t* cr);
+#endif
+
   // Compute the size required to draw some text with the provided font.
   // Attempts to fit the text with the provided width and height. Increases
   // height and then width as needed to make the text fit. This method
diff --git a/chrome/common/gfx/chrome_canvas_linux.cc b/chrome/common/gfx/chrome_canvas_linux.cc
index 93a32f7..5f8b430 100644
--- a/chrome/common/gfx/chrome_canvas_linux.cc
+++ b/chrome/common/gfx/chrome_canvas_linux.cc
@@ -58,6 +58,18 @@ void ChromeCanvas::SizeStringInt(const std::wstring& text,
   NOTIMPLEMENTED();
 }
 
+void ChromeCanvas::ApplySkiaMatrixToCairoContext(cairo_t* cr) {
+  const SkMatrix& skia_matrix = getTotalMatrix();
+  cairo_matrix_t cairo_matrix;
+  cairo_matrix_init(&cairo_matrix,
+                    SkScalarToFloat(skia_matrix.getScaleX()),
+                    SkScalarToFloat(skia_matrix.getSkewY()),
+                    SkScalarToFloat(skia_matrix.getSkewX()),
+                    SkScalarToFloat(skia_matrix.getScaleY()),
+                    SkScalarToFloat(skia_matrix.getTranslateX()),
+                    SkScalarToFloat(skia_matrix.getTranslateY()));
+  cairo_set_matrix(cr, &cairo_matrix);
+}
 
 void ChromeCanvas::DrawStringInt(const std::wstring& text,
                                  const ChromeFont& font,
@@ -65,6 +77,10 @@ void ChromeCanvas::DrawStringInt(const std::wstring& text,
                                  int h, int flags) {
   cairo_surface_t* surface = beginPlatformPaint();
   cairo_t* cr = cairo_create(surface);
+  // We're going to draw onto the surface directly. This circumvents the matrix
+  // installed by Skia. Apply the matrix from skia to cairo so they align and
+  // we draw at the right place.
+  ApplySkiaMatrixToCairoContext(cr);
   PangoLayout* layout = pango_cairo_create_layout(cr);
 
   cairo_set_source_rgb(cr,
diff --git a/skia/ext/platform_canvas_linux.h b/skia/ext/platform_canvas_linux.h
index 686ad0a..1f237d7 100644
--- a/skia/ext/platform_canvas_linux.h
+++ b/skia/ext/platform_canvas_linux.h
@@ -95,7 +95,7 @@ class CanvasPaintT : public T {
 
       // Blit the dirty rect to the window.
       cairo_t* cr = gdk_cairo_create(window_);
-      cairo_set_source_surface(cr, surface_, 0.0, 0.0);
+      cairo_set_source_surface(cr, surface_, rectangle_.x, rectangle_.y);
       cairo_rectangle(cr, rectangle_.x, rectangle_.y,
                       rectangle_.width, rectangle_.height);
       cairo_fill(cr);
@@ -115,16 +115,15 @@ class CanvasPaintT : public T {
 
  private:
   void init(bool opaque) {
-    // In order to be most optimal, we could allocate just the damaged rect and
-    // set a translation so it's at the origin.  However, since that would be
-    // ignored when we draw on the cairo surface, this currently won't work.
-    // Allocate the minimal bitmap from the origin to damage rect.
-    if (!T::initialize(rectangle_.x + rectangle_.width,
-                       rectangle_.y + rectangle_.height, opaque, NULL)) {
+    if (!T::initialize(rectangle_.width, rectangle_.height, opaque, NULL)) {
       // Cause a deliberate crash;
       *(char*) 0 = 0;
     }
 
+    // Need to translate so that the dirty region appears at the origin of the
+    // surface.
+    T::translate(-SkIntToScalar(rectangle_.x), -SkIntToScalar(rectangle_.y));
+
     surface_ = T::getTopPlatformDevice().beginPlatformPaint();
   }