Changeset 213727 in webkit

Timestamp:

Mar 10, 2017 12:25:40 PM (7 years ago)

Author:

pvollan@apple.com

Message:

[Win] Scrollbars buttons have incorrect size in HiDPI.
​https://bugs.webkit.org/show_bug.cgi?id=169463

Reviewed by Alex Christensen.

There seems to be a bug in DrawThemeBackground when the device context is scaled.
We can work around this by scaling the drawing rectangle instead.

• platform/win/ScrollbarThemeWin.cpp:

(WebCore::ScrollbarThemeWin::paintButton):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/win/ScrollbarThemeWin.cpp (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2017-03-10  Per Arne Vollan  <pvollan@apple.com>
+
+        [Win] Scrollbars buttons have incorrect size in HiDPI.
+        https://bugs.webkit.org/show_bug.cgi?id=169463
+
+        Reviewed by Alex Christensen.
+
+        There seems to be a bug in DrawThemeBackground when the device context is scaled.
+        We can work around this by scaling the drawing rectangle instead.
+ 
+        * platform/win/ScrollbarThemeWin.cpp:
+        (WebCore::ScrollbarThemeWin::paintButton):
+
 2017-03-10  Zalan Bujtas  <zalan@apple.com>
 

trunk/Source/WebCore/platform/win/ScrollbarThemeWin.cpp

@@ -332 +332 @@
         alphaBlend = IsThemeBackgroundPartiallyTransparent(scrollbarTheme, SP_BUTTON, xpState);
 
-    LocalWindowsContext windowsContext(context, rect, alphaBlend);
-    RECT themeRect(rect);
-    if (scrollbarTheme)
-        DrawThemeBackground(scrollbarTheme, windowsContext.hdc(), SP_BUTTON, xpState, &themeRect, 0);
-    else
-        ::DrawFrameControl(windowsContext.hdc(), &themeRect, DFC_SCROLL, classicState);
-
-    if (!alphaBlend && !context.isInTransparencyLayer())
-        DIBPixelData::setRGBABitmapAlpha(windowsContext.hdc(), rect, 255);
+    // There seems to be a bug in DrawThemeBackground when the device context is scaled.
+    // We can work around this by scaling the drawing rectangle instead.
+    auto scaleFactor = context.scaleFactor().width();
+    auto scaledRect = rect;
+    scaledRect.scale(scaleFactor);
+    context.save();
+    context.scale(FloatSize(1.0f / scaleFactor, 1.0f / scaleFactor));
+
+    {
+        LocalWindowsContext windowsContext(context, scaledRect, alphaBlend);
+        RECT themeRect(scaledRect);
+        if (scrollbarTheme)
+            DrawThemeBackground(scrollbarTheme, windowsContext.hdc(), SP_BUTTON, xpState, &themeRect, 0);
+        else
+            ::DrawFrameControl(windowsContext.hdc(), &themeRect, DFC_SCROLL, classicState);
+
+        if (!alphaBlend && !context.isInTransparencyLayer())
+            DIBPixelData::setRGBABitmapAlpha(windowsContext.hdc(), scaledRect, 255);
+    }
+    context.restore();
 }