cros: Refactor MagnifierGlass to take border parameters.

When users select a capture region in Capture Mode, they can fine tune
it. To make this process more precise, we display a magnifying glass
at their cursor. Currently the MagnifierGlass uses hard-coded values to
draw its border which don't match Capture Mode's spec.

This CL refactors MagnifierGlass to take parameters for its border so
the magnifying glass for the capture region can be up-to-spec.

Test: manual
Bug: 1133751
Change-Id: I4867176e4a32e9f8271cf1168846caf37ca5d6b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2454269Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Jeremy Chinsen <chinsenj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814428}

ash/magnifier/magnifier_glass.cc

@@ -16,23 +16,6 @@
 namespace ash {
 namespace {
 
-// Size of the border around the magnifying glass in DIP.
-constexpr int kBorderSize = 10;
-// Thickness of the outline around magnifying glass border in DIP.
-constexpr int kBorderOutlineThickness = 1;
-// Thickness of the shadow around the magnifying glass in DIP.
-constexpr int kShadowThickness = 24;
-// Offset of the shadow around the magnifying glass in DIP. One of the shadows
-// is lowered a bit, so we have to include |kShadowOffset| in our calculations
-// to compensate.
-constexpr int kShadowOffset = 24;
-// The color of the border and its outlines. The border has an outline on both
-// sides, producing a black/white/black ring.
-constexpr SkColor kBorderColor = SkColorSetARGB(204, 255, 255, 255);
-constexpr SkColor kBorderOutlineColor = SkColorSetARGB(51, 0, 0, 0);
-// The colors of the two shadow around the magnifiying glass.
-constexpr SkColor kTopShadowColor = SkColorSetARGB(26, 0, 0, 0);
-constexpr SkColor kBottomShadowColor = SkColorSetARGB(61, 0, 0, 0);
 // Inset on the zoom filter.
 constexpr int kZoomInset = 0;
 // Vertical offset between the center of the magnifier and the tip of the
@@ -43,14 +26,23 @@ constexpr int kVerticalOffset = 0;
 // Name of the magnifier window.
 constexpr char kMagniferGlassWindowName[] = "MagnifierGlassWindow";
 
+int GetShadowOffset(const MagnifierGlass::Params& params) {
+  return std::max(params.bottom_shadow.y(), params.top_shadow.y());
+}
+
+int GetShadowThickness(const MagnifierGlass::Params& params) {
+  return std::max(params.bottom_shadow.blur(), params.top_shadow.blur());
+}
+
 gfx::Size GetWindowSize(const MagnifierGlass::Params& params) {
   // The diameter of the window is the diameter of the magnifier, border and
-  // shadow combined. We apply |kShadowOffset| on all sides even though the
-  // shadow is only thicker on the bottom so as to keep the circle centered in
-  // the view and keep calculations (border rendering and content masking)
-  // simpler.
-  int window_diameter =
-      (params.radius + kBorderSize + kShadowThickness + kShadowOffset) * 2;
+  // shadow combined. We apply the larger shadow offset on all sides, despite
+  // the shadow offsets potentially being unequal, so as to keep the circle
+  // centered in the view and keep calculations (border rendering and content
+  // masking) simpler.
+  int window_diameter = (params.radius + params.border_size +
+                         GetShadowThickness(params) + GetShadowOffset(params)) *
+                        2;
   return gfx::Size(window_diameter, window_diameter);
 }
 
@@ -69,12 +61,11 @@ gfx::Rect GetBounds(const MagnifierGlass::Params& params,
 // the shadow.
 class MagnifierGlass::BorderRenderer : public ui::LayerDelegate {
  public:
-  BorderRenderer(const gfx::Rect& window_bounds, int radius)
-      : magnifier_window_bounds_(window_bounds), radius_(radius) {
-    magnifier_shadows_.push_back(gfx::ShadowValue(
-        gfx::Vector2d(0, kShadowOffset), kShadowThickness, kBottomShadowColor));
-    magnifier_shadows_.push_back(gfx::ShadowValue(
-        gfx::Vector2d(0, 0), kShadowThickness, kTopShadowColor));
+  BorderRenderer(const gfx::Rect& window_bounds,
+                 const MagnifierGlass::Params& params)
+      : magnifier_window_bounds_(window_bounds), params_(params) {
+    magnifier_shadows_.push_back(params_.bottom_shadow);
+    magnifier_shadows_.push_back(params_.top_shadow);
   }
 
   ~BorderRenderer() override = default;
@@ -90,13 +81,14 @@ class MagnifierGlass::BorderRenderer : public ui::LayerDelegate {
     shadow_flags.setColor(SK_ColorTRANSPARENT);
     shadow_flags.setLooper(gfx::CreateShadowDrawLooper(magnifier_shadows_));
     gfx::Rect shadow_bounds(magnifier_window_bounds_.size());
-    recorder.canvas()->DrawCircle(
-        shadow_bounds.CenterPoint(),
-        shadow_bounds.width() / 2 - kShadowThickness - kShadowOffset,
-        shadow_flags);
+    recorder.canvas()->DrawCircle(shadow_bounds.CenterPoint(),
+                                  shadow_bounds.width() / 2 -
+                                      GetShadowThickness(params_) -
+                                      GetShadowOffset(params_),
+                                  shadow_flags);
 
     // The radius of the magnifier and its border.
-    const int magnifier_radius = radius_ + kBorderSize;
+    const int magnifier_radius = params_.radius + params_.border_size;
 
     // Clear the shadow for the magnified area.
     cc::PaintFlags mask_flags;
@@ -105,36 +97,36 @@ class MagnifierGlass::BorderRenderer : public ui::LayerDelegate {
     mask_flags.setStyle(cc::PaintFlags::kFill_Style);
     recorder.canvas()->DrawCircle(
         magnifier_window_bounds_.CenterPoint(),
-        magnifier_radius - kBorderOutlineThickness / 2, mask_flags);
+        magnifier_radius - params_.border_outline_thickness / 2, mask_flags);
 
     cc::PaintFlags border_flags;
     border_flags.setAntiAlias(true);
     border_flags.setStyle(cc::PaintFlags::kStroke_Style);
 
     // Draw the inner border.
-    border_flags.setStrokeWidth(kBorderSize);
-    border_flags.setColor(kBorderColor);
+    border_flags.setStrokeWidth(params_.border_size);
+    border_flags.setColor(params_.border_color);
     recorder.canvas()->DrawCircle(magnifier_window_bounds_.CenterPoint(),
-                                  magnifier_radius - kBorderSize / 2,
+                                  magnifier_radius - params_.border_size / 2,
                                   border_flags);
 
     // Draw border outer outline and then draw the border inner outline.
-    border_flags.setStrokeWidth(kBorderOutlineThickness);
-    border_flags.setColor(kBorderOutlineColor);
+    border_flags.setStrokeWidth(params_.border_outline_thickness);
+    border_flags.setColor(params_.border_outline_color);
     recorder.canvas()->DrawCircle(
         magnifier_window_bounds_.CenterPoint(),
-        magnifier_radius - kBorderOutlineThickness / 2, border_flags);
-    recorder.canvas()->DrawCircle(
-        magnifier_window_bounds_.CenterPoint(),
-        magnifier_radius - kBorderSize + kBorderOutlineThickness / 2,
-        border_flags);
+        magnifier_radius - params_.border_outline_thickness / 2, border_flags);
+    recorder.canvas()->DrawCircle(magnifier_window_bounds_.CenterPoint(),
+                                  magnifier_radius - params_.border_size +
+                                      params_.border_outline_thickness / 2,
+                                  border_flags);
   }
 
   void OnDeviceScaleFactorChanged(float old_device_scale_factor,
                                   float new_device_scale_factor) override {}
 
   const gfx::Rect magnifier_window_bounds_;
-  const int radius_;
+  const Params params_;
   std::vector<gfx::ShadowValue> magnifier_shadows_;
 
   DISALLOW_COPY_AND_ASSIGN(BorderRenderer);
@@ -219,8 +211,7 @@ void MagnifierGlass::CreateMagnifierWindow(aura::Window* root_window,
 
   border_layer_ = std::make_unique<ui::Layer>();
   border_layer_->SetBounds(window_bounds);
-  border_renderer_ =
-      std::make_unique<BorderRenderer>(window_bounds, params_.radius);
+  border_renderer_ = std::make_unique<BorderRenderer>(window_bounds, params_);
   border_layer_->set_delegate(border_renderer_.get());
   border_layer_->SetFillsBoundsOpaquely(false);
   root_layer->Add(border_layer_.get());

ash/magnifier/magnifier_glass.h

@@ -10,6 +10,7 @@
 #include "ash/ash_export.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_observer.h"
+#include "ui/gfx/shadow_value.h"
 #include "ui/views/widget/widget_observer.h"
 
 namespace gfx {
@@ -31,6 +32,19 @@ class ASH_EXPORT MagnifierGlass : public aura::WindowObserver,
     float scale = 2.f;
     // Radius of the magnifying glass in DIP.
     int radius = 64;
+    // Size of the border around the magnifying glass in DIP.
+    int border_size = 10;
+    // Thickness of the outline around magnifying glass border in DIP.
+    int border_outline_thickness = 1;
+    // The color of the border and its outlines. The border has an outline on
+    // both sides, producing a black/white/black ring.
+    SkColor border_color = SkColorSetARGB(204, 255, 255, 255);
+    SkColor border_outline_color = SkColorSetARGB(51, 0, 0, 0);
+    // The shadow values for the border.
+    gfx::ShadowValue bottom_shadow =
+        gfx::ShadowValue(gfx::Vector2d(0, 24), 24, SkColorSetARGB(61, 0, 0, 0));
+    gfx::ShadowValue top_shadow =
+        gfx::ShadowValue(gfx::Vector2d(0, 0), 24, SkColorSetARGB(26, 0, 0, 0));
   };
 
   explicit MagnifierGlass(Params params);