Draw infobar arrow border with width of 1px on any scale factor.

chrome/browser/ui/views/infobars/infobar_background.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 "chrome/browser/ui/views/infobars/infobar_background.h"
 
 #include "chrome/browser/ui/infobar_container_delegate.h"
 #include "chrome/browser/ui/views/infobars/infobar_view.h"
 #include "components/infobars/core/infobar.h"
 #include "third_party/skia/include/effects/SkGradientShader.h"
+#include "ui/base/material_design/material_design_controller.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_utils.h"
+#include "ui/gfx/scoped_canvas.h"
 #include "ui/views/view.h"
 
 InfoBarBackground::InfoBarBackground(
     infobars::InfoBarDelegate::Type infobar_type)
-    : separator_color_(SK_ColorBLACK),
-      top_color_(infobars::InfoBar::GetTopColor(infobar_type)),
+    : top_color_(infobars::InfoBar::GetTopColor(infobar_type)),
       bottom_color_(infobars::InfoBar::GetBottomColor(infobar_type)) {
   SetNativeControlColor(
       color_utils::AlphaBlend(top_color_, bottom_color_, 128));
 }
 
 InfoBarBackground::~InfoBarBackground() {
 }
 
 void InfoBarBackground::Paint(gfx::Canvas* canvas, views::View* view) const {
+  if (ui::MaterialDesignController::IsModeMaterial()) {
+    PaintMd(canvas, view);
+    return;
+  }
+
   SkPoint gradient_points[2];
   gradient_points[0].iset(0, 0);
   gradient_points[1].iset(0, view->height());
-  SkColor gradient_colors[2] = { top_color_, bottom_color_ };
+  SkColor gradient_colors[2] = {top_color_, bottom_color_};
   SkPaint paint;
   paint.setStrokeWidth(
       SkIntToScalar(InfoBarContainerDelegate::kSeparatorLineHeight));
   paint.setStyle(SkPaint::kFill_Style);
   paint.setStrokeCap(SkPaint::kRound_Cap);
   paint.setShader(SkGradientShader::MakeLinear(
-      gradient_points, gradient_colors, NULL, 2, SkShader::kClamp_TileMode));
+      gradient_points, gradient_colors, nullptr, 2, SkShader::kClamp_TileMode));
 
+  SkCanvas* canvas_skia = canvas->sk_canvas();
   InfoBarView* infobar = static_cast<InfoBarView*>(view);
-  SkCanvas* canvas_skia = canvas->sk_canvas();
   canvas_skia->drawPath(infobar->fill_path(), paint);
 
-  paint.setShader(NULL);
-  paint.setColor(SkColorSetA(separator_color_,
-                             SkColorGetA(gradient_colors[0])));
+  paint.setShader(nullptr);
+  SkColor separator_color =
+      infobar->container_delegate()->GetInfoBarSeparatorColor();
+  paint.setColor(SkColorSetA(separator_color, SkColorGetA(gradient_colors[0])));
   paint.setStyle(SkPaint::kStroke_Style);
   // Anti-alias the path so it doesn't look goofy when the edges are not at 45
   // degree angles, but don't anti-alias anything else, especially not the fill,
   // lest we get weird color bleeding problems.
   paint.setAntiAlias(true);
   canvas_skia->drawPath(infobar->stroke_path(), paint);
   paint.setAntiAlias(false);
 
   // Now draw the separator at the bottom.
   canvas->FillRect(
       gfx::Rect(0,
                 view->height() - InfoBarContainerDelegate::kSeparatorLineHeight,
                 view->width(), InfoBarContainerDelegate::kSeparatorLineHeight),
-      separator_color_);
+      separator_color);
 }
+
+void InfoBarBackground::PaintMd(gfx::Canvas* canvas, views::View* view) const {
+  InfoBarView* infobar = static_cast<InfoBarView*>(view);
+  const infobars::InfoBarContainer::Delegate* delegate =
+      infobar->container_delegate();
+  SkPath stroke_path, fill_path;
+  SkColor separator_color = SK_ColorBLACK;
+  if (delegate) {
+    separator_color = delegate->GetInfoBarSeparatorColor();
+    int arrow_x;
+    if (delegate->DrawInfoBarArrows(&arrow_x) && infobar->arrow_height() > 0) {
+      SkScalar arrow_fill_height = SkIntToScalar(infobar->arrow_height());
+      SkScalar arrow_fill_half_width =
+          SkIntToScalar(infobar->arrow_half_width());
+      stroke_path.moveTo(SkIntToScalar(arrow_x) - arrow_fill_half_width,
+                         SkIntToScalar(infobar->arrow_height()));
+      stroke_path.rLineTo(arrow_fill_half_width, -arrow_fill_height);
+      stroke_path.rLineTo(arrow_fill_half_width, arrow_fill_height);
+
+      fill_path = stroke_path;
+      fill_path.close();
+    }
+  }
+  fill_path.addRect(0, SkIntToScalar(infobar->arrow_height()),
+                    SkIntToScalar(infobar->width()),
+                    SkIntToScalar(infobar->height()));
+
+  gfx::ScopedCanvas scoped(canvas);
+  // Undo the scale factor so we can stroke with a width of 1px (not 1dp).
+  const float scale = canvas->UndoDeviceScaleFactor();
+  // View bounds are in dp. Manually scale for px.
+  gfx::SizeF view_size_px = gfx::ScaleSize(gfx::SizeF(view->size()), scale);
+
+  SkPaint fill;
+  fill.setStyle(SkPaint::kFill_Style);
+  fill.setColor(top_color_);
+
+  SkCanvas* canvas_skia = canvas->sk_canvas();
+  // The paths provided by the above calculations are in dp. Manually scale for
+  // px.
+  SkMatrix dsf_transform;
+  dsf_transform.setScale(SkFloatToScalar(scale), SkFloatToScalar(scale));
+  fill_path.transform(dsf_transform);
+  // In order to affect exactly the pixels we want, the fill and stroke paths
+  // need to go through the pixel centers instead of along the pixel
+  // edges/corners. Skia considers integral coordinates to be the edges between
+  // pixels, so offset by 0.5 to get to the centers.
+  fill_path.offset(SK_ScalarHalf, SK_ScalarHalf);
+  canvas_skia->drawPath(fill_path, fill);
+
+  SkPaint stroke;
+  stroke.setStyle(SkPaint::kStroke_Style);
+  const int kSeparatorThicknessPx = 1;
+  stroke.setStrokeWidth(SkIntToScalar(kSeparatorThicknessPx));
+  stroke.setColor(separator_color);
+  stroke_path.transform(dsf_transform);
+  stroke_path.offset(SK_ScalarHalf, SK_ScalarHalf);
+
+  // The arrow part of the top separator. (The rest was drawn by the toolbar or
+  // the infobar above this one.)
+  stroke.setAntiAlias(true);
+  canvas_skia->drawPath(stroke_path, stroke);
+  // Bottom separator.
+  stroke.setAntiAlias(false);
+  SkScalar y = SkIntToScalar(view_size_px.height() - kSeparatorThicknessPx) +
+               SK_ScalarHalf;
+  SkScalar w = SkIntToScalar(view_size_px.width());
+  canvas_skia->drawLine(0, y, w, y, stroke);
+}