High DPI support for themes: Raw images for NTP attribution and background

chrome/browser/themes/browser_theme_pack.cc

Index: chrome/browser/themes/browser_theme_pack.cc
diff --git a/chrome/browser/themes/browser_theme_pack.cc b/chrome/browser/themes/browser_theme_pack.cc
index e2a71228b328f9049ffcea10887346c88a8ca267..b2cb84a08d6ae94241b1ae5fcf805c985c9b53d0 100644
--- a/chrome/browser/themes/browser_theme_pack.cc
+++ b/chrome/browser/themes/browser_theme_pack.cc
@@ -32,6 +32,7 @@
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/image/image_skia_operations.h"
 #include "ui/gfx/screen.h"
+#include "ui/gfx/size_conversions.h"
 #include "ui/gfx/skia_util.h"
 
 using content::BrowserThread;
@@ -582,6 +583,11 @@ scoped_refptr<BrowserThemePack> BrowserThemePack::BuildFromExtension(
     it->second = gfx::Image(image_skia);
   }
 
+  // Generate raw images (for new-tab-page attribution and background) for
+  // any missing scale from an available scale image.
+  pack->GenerateRawImageForAllScales(PRS_THEME_NTP_BACKGROUND);
+  pack->GenerateRawImageForAllScales(PRS_THEME_NTP_ATTRIBUTION);
+
   // The BrowserThemePack is now in a consistent state.
   return pack;
 }
@@ -1443,3 +1449,111 @@ bool BrowserThemePack::GetScaleFactorFromManifestKey(
   }
   return false;
 }
+
+void BrowserThemePack::GenerateRawImageForAllScales(int prs_id) {

[pkotwicz, 2013/06/07 16:15:26]

Nit: Rename to GenerateRawImagesForAllSupportedScaleFactors().

[sschmitz, 2013/06/07 21:13:54]

Done.

+  // For any raw theme image for a scale that is not in the theme
+  // extension we compute (by scaling) an image based on an available
+  // image. For expediency we choose only one image to be used for
+  // all missing scales. (On Chrome OS there are only two scales).
+  // First we attempt to find an available image with a scale that is
+  // the smallest scale larger than the largest missing scale.
+  // If no such image is available, we attempt to find an available
+  // image with a scale that is the largest scale smaller than the
+  // highest missing scale.
+
+  // Find highest missing scale.
+  ui::ScaleFactor highest_missing = ui::SCALE_FACTOR_NONE;
+  for (size_t i = 0; i < scale_factors_.size(); ++i) {
+    int raw_id = GetRawIDByPersistentID(prs_id, scale_factors_[i]);
+    if ((highest_missing == ui::SCALE_FACTOR_NONE ||
+         (ui::GetScaleFactorScale(scale_factors_[i]) >
+          ui::GetScaleFactorScale(highest_missing))) &&
+        image_memory_.find(raw_id) == image_memory_.end()) {
+      highest_missing = scale_factors_[i];
+    }
+  }
+  // If no image is missing, we're done.
+  if (highest_missing == ui::SCALE_FACTOR_NONE)
+    return;
+
+  // Find lowest available scale that is larger than highest missing.
+  ui::ScaleFactor available = ui::SCALE_FACTOR_NONE;
+  for (size_t i = 0; i < scale_factors_.size(); ++i) {
+    int raw_id = GetRawIDByPersistentID(prs_id, scale_factors_[i]);

[pkotwicz, 2013/06/07 16:15:26]

I think you can just go and find the image for |prs_id| with the largest scale
factor. The image with the scale factor closest to |highest_missing| is not
necessarily the best choice. For instance, an image whose scale factor is an
integer multiple of the missing scale factor(s) is a better choice.

[sschmitz, 2013/06/07 21:13:54]

Done.

+    if ((ui::GetScaleFactorScale(scale_factors_[i]) >
+         ui::GetScaleFactorScale(highest_missing)) &&
+        (available == ui::SCALE_FACTOR_NONE ||
+         (ui::GetScaleFactorScale(scale_factors_[i]) <
+          ui::GetScaleFactorScale(available))) &&
+        image_memory_.find(raw_id) != image_memory_.end()) {
+      available = scale_factors_[i];
+    }
+  }
+
+  if (available == ui::SCALE_FACTOR_NONE) {
+    // find the highest available scale that is smaller than highest missing
+    for (size_t i = 0; i < scale_factors_.size(); ++i) {
+      int raw_id = GetRawIDByPersistentID(prs_id, scale_factors_[i]);
+      if ((ui::GetScaleFactorScale(scale_factors_[i]) <
+           ui::GetScaleFactorScale(highest_missing)) &&
+          (available == ui::SCALE_FACTOR_NONE ||
+           (ui::GetScaleFactorScale(scale_factors_[i]) >
+            ui::GetScaleFactorScale(available))) &&
+          image_memory_.find(raw_id) != image_memory_.end()) {
+        available = scale_factors_[i];
+      }
+    }
+  }
+
+  // If no image is available, we're done.
+  if (available == ui::SCALE_FACTOR_NONE)
+    return;
+
+  // Now fill in all missing scales.
+  int available_raw_id = GetRawIDByPersistentID(prs_id, available);
+  RawImages::const_iterator it = image_memory_.find(available_raw_id);
+  DCHECK(it != image_memory_.end());
+  DCHECK(it->second->size() > 0);
+  SkBitmap available_bitmap;
+  for (size_t i = 0; i < scale_factors_.size(); ++i) {
+    if (scale_factors_[i] == available)

[pkotwicz, 2013/06/07 16:15:26]

You don't need the if on line 1519 because the if on line 1522 will catch this
case too.

[sschmitz, 2013/06/07 21:13:54]

Done.

+      continue;
+    int scaled_raw_id = GetRawIDByPersistentID(prs_id, scale_factors_[i]);
+    if (image_memory_.find(scaled_raw_id) != image_memory_.end())
+      continue;
+    if (available_bitmap.isNull()) {
+      if (!gfx::PNGCodec::Decode(it->second->front(),

[pkotwicz, 2013/06/07 16:15:26]

You know that you need |available_bitmap| because you exit early on line  1477.
Can you move the bitmap initialization outside of the loop?

[sschmitz, 2013/06/07 21:13:54]

Done.

+                                 it->second->size(),
+                                 &available_bitmap)) {
+        NOTREACHED() << "Unable to decode theme image for prs_id="
+                     << prs_id << " for scale_factor=" << available;
+        break;
+      }
+    }
+    gfx::Size scaled_size = gfx::ToCeiledSize(
+        gfx::ScaleSize(gfx::Size(available_bitmap.width(),
+                                 available_bitmap.height()),
+                       ui::GetScaleFactorScale(scale_factors_[i]) /
+                       ui::GetScaleFactorScale(available)));
+    SkBitmap scaled_bitmap;
+    scaled_bitmap.setConfig(SkBitmap::kARGB_8888_Config,
+                            scaled_size.width(),
+                            scaled_size.height());
+    if (!scaled_bitmap.allocPixels())
+      SK_CRASH();
+    scaled_bitmap.eraseARGB(0, 0, 0, 0);
+    SkCanvas canvas(scaled_bitmap);
+    SkRect scaled_bounds = RectToSkRect(gfx::Rect(scaled_size));
+    canvas.drawBitmapRect(available_bitmap, NULL, scaled_bounds);
+    std::vector<unsigned char> bitmap_data;
+    if (!gfx::PNGCodec::EncodeBGRASkBitmap(scaled_bitmap,
+                                           false,
+                                           &bitmap_data)) {
+      NOTREACHED() << "Unable to encode theme image for prs_id="
+                   << prs_id << " for scale_factor=" << scale_factors_[i];
+      break;
+    }
+    image_memory_[scaled_raw_id] =
+        base::RefCountedBytes::TakeVector(&bitmap_data);
+  }
+}