aura-x11: Add custom web cursor support.

webkit/glue/webcursor_aurax11.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "webkit/glue/webcursor.h"
+
+#include <X11/Xlib.h>
+#include <X11/Xcursor/Xcursor.h>
+#include <X11/cursorfont.h>
+
+#include "base/logging.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebCursorInfo.h"
+#include "third_party/skia/include/core/SkUnPreMultiply.h"
+#include "ui/aura/cursor.h"
+#include "ui/base/x/x11_util.h"
+
+const gfx::PlatformCursor& WebCursor::GetPlatformCursor() {
+  if (platform_cursor_)
+    return platform_cursor_;
+
+  SkBitmap bitmap;
+  bitmap.setConfig(SkBitmap::kARGB_8888_Config,
+                   custom_size_.width(), custom_size_.height());
+  bitmap.allocPixels();
+  memcpy(bitmap.getAddr32(0, 0), custom_data_.data(), custom_data_.size());
+
+  Display* xdisplay = ui::GetXDisplay();
+  image_ = XcursorImageCreate(custom_size_.width(), custom_size_.height());
+  image_->xhot = hotspot_.x();
+  image_->yhot = hotspot_.y();
+  uint8* pixels = (uint8*)image_->pixels;

[darin (slow to review), 2012/02/24 06:32:35]

nit: use C++ style cast

+  // SkBitmaps are premultiplied, we need to unpremultiply them.

[darin (slow to review), 2012/02/24 06:32:35]

is there really no common routine somewhere to unpremultiply a SkBitmap? 
really?  not in skia somewhere or elsewhere in chrome?  is there really no other
place in the code where we do this? :-)

[sadrul, 2012/02/24 17:38:19]

Indeed there is, for GTK+. In my effort to refactor this code now, I realized
that this code works well for GTK+, however it doesn't work well for these X
cursors (the color is not always right). I have changed this code to work
correctly and tested this more (e.g.
http://www.w3schools.com/cssref/playit.asp?filename=playcss_cursor).

+  const int kBytesPerPixel = 4;
+
+  bitmap.lockPixels();
+  int height = bitmap.height(), width = bitmap.width();
+  for (int y = 0, i = 0; y < height; y++) {
+    for (int x = 0; x < width; x++) {
+      uint32 pixel = bitmap.getAddr32(0, y)[x];
+
+      int alpha = SkColorGetA(pixel);
+      if (alpha != 0 && alpha != 255) {
+        SkColor unmultiplied = SkUnPreMultiply::PMColorToColor(pixel);
+        pixels[i + 0] = SkColorGetR(unmultiplied);
+        pixels[i + 1] = SkColorGetG(unmultiplied);
+        pixels[i + 2] = SkColorGetB(unmultiplied);
+        pixels[i + 3] = alpha;
+      } else {
+        pixels[i + 0] = SkColorGetR(pixel);
+        pixels[i + 1] = SkColorGetG(pixel);
+        pixels[i + 2] = SkColorGetB(pixel);
+        pixels[i + 3] = alpha;
+      }
+      i += kBytesPerPixel;
+    }
+  }
+  bitmap.unlockPixels();
+
+  platform_cursor_ = XcursorImageLoadCursor(xdisplay, image_);
+  return platform_cursor_;
+}
+
+void WebCursor::InitPlatformData() {
+  platform_cursor_ = 0;
+  image_ = NULL;
+}
+
+bool WebCursor::SerializePlatformData(Pickle* pickle) const {
+  return true;

[darin (slow to review), 2012/02/24 06:32:35]

nit: should these assert not reached?

[sadrul, 2012/02/24 17:38:19]

I am unsure if we want to NOTREACHED here. So I kept it as it was before this
change.

+}
+
+bool WebCursor::DeserializePlatformData(const Pickle* pickle, void** iter) {
+  return true;
+}
+
+bool WebCursor::IsPlatformDataEqual(const WebCursor& other) const {
+  return true;
+}
+
+void WebCursor::CleanupPlatformData() {
+  if (platform_cursor_) {
+    XFreeCursor(ui::GetXDisplay(), platform_cursor_);
+    platform_cursor_ = 0;
+  }
+
+  if (image_) {
+    XcursorImageDestroy(image_);
+    image_ = NULL;
+  }
+}
+
+void WebCursor::CopyPlatformData(const WebCursor& other) {
+  platform_cursor_ = other.platform_cursor_;
+}