diff -r 000000000000 -r 6474c204b198 widget/windows/TaskbarPreview.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/widget/windows/TaskbarPreview.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,428 @@
+/* vim: se cin sw=2 ts=2 et : */
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "TaskbarPreview.h"
+#include <nsITaskbarPreviewController.h>
+#include <windows.h>
+
+#include <nsError.h>
+#include <nsCOMPtr.h>
+#include <nsIWidget.h>
+#include <nsIBaseWindow.h>
+#include <nsIObserverService.h>
+#include <nsServiceManagerUtils.h>
+
+#include "nsUXThemeData.h"
+#include "nsWindow.h"
+#include "nsAppShell.h"
+#include "TaskbarPreviewButton.h"
+#include "WinUtils.h"
+#include "gfxWindowsPlatform.h"
+
+#include <nsIBaseWindow.h>
+#include <nsICanvasRenderingContextInternal.h>
+#include "mozilla/dom/CanvasRenderingContext2D.h"
+#include <imgIContainer.h>
+#include <nsIDocShell.h>
+
+#include "mozilla/Telemetry.h"
+
+// Defined in dwmapi in a header that needs a higher numbered _WINNT #define
+#define DWM_SIT_DISPLAYFRAME 0x1
+
+namespace mozilla {
+namespace widget {
+
+namespace {
+
+// Shared by all TaskbarPreviews to avoid the expensive creation process.
+// Manually refcounted (see gInstCount) by the ctor and dtor of TaskbarPreview.
+// This is done because static constructors aren't allowed for perf reasons.
+dom::CanvasRenderingContext2D* gCtx = nullptr;
+// Used in tracking the number of previews. Used in freeing
+// the static 2d rendering context on shutdown.
+uint32_t gInstCount = 0;
+
+/* Helper method to lazily create a canvas rendering context and associate a given
+ * surface with it.
+ *
+ * @param shell The docShell used by the canvas context for text settings and other
+ *              misc things.
+ * @param surface The gfxSurface backing the context
+ * @param width The width of the given surface
+ * @param height The height of the given surface
+ */
+nsresult
+GetRenderingContext(nsIDocShell *shell, gfxASurface *surface,
+                    uint32_t width, uint32_t height) {
+  if (!gCtx) {
+    // create the canvas rendering context
+    Telemetry::Accumulate(Telemetry::CANVAS_2D_USED, 1);
+    gCtx = new mozilla::dom::CanvasRenderingContext2D();
+    NS_ADDREF(gCtx);
+  }
+
+  // Set the surface we'll use to render.
+  return gCtx->InitializeWithSurface(shell, surface, width, height);
+}
+
+/* Helper method for freeing surface resources associated with the rendering context.
+ */
+void
+ResetRenderingContext() {
+  if (!gCtx)
+    return;
+
+  if (NS_FAILED(gCtx->Reset())) {
+    NS_RELEASE(gCtx);
+    gCtx = nullptr;
+  }
+}
+
+}
+
+TaskbarPreview::TaskbarPreview(ITaskbarList4 *aTaskbar, nsITaskbarPreviewController *aController, HWND aHWND, nsIDocShell *aShell)
+  : mTaskbar(aTaskbar),
+    mController(aController),
+    mWnd(aHWND),
+    mVisible(false),
+    mDocShell(do_GetWeakReference(aShell))
+{
+  // TaskbarPreview may outlive the WinTaskbar that created it
+  ::CoInitialize(nullptr);
+
+  gInstCount++;
+
+  WindowHook &hook = GetWindowHook();
+  hook.AddMonitor(WM_DESTROY, MainWindowHook, this);
+}
+
+TaskbarPreview::~TaskbarPreview() {
+  // Avoid dangling pointer
+  if (sActivePreview == this)
+    sActivePreview = nullptr;
+
+  // Our subclass should have invoked DetachFromNSWindow already.
+  NS_ASSERTION(!mWnd, "TaskbarPreview::DetachFromNSWindow was not called before destruction");
+
+  // Make sure to release before potentially uninitializing COM
+  mTaskbar = nullptr;
+
+  if (--gInstCount == 0)
+    NS_IF_RELEASE(gCtx);
+
+  ::CoUninitialize();
+}
+
+NS_IMETHODIMP
+TaskbarPreview::SetController(nsITaskbarPreviewController *aController) {
+  NS_ENSURE_ARG(aController);
+
+  mController = aController;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TaskbarPreview::GetController(nsITaskbarPreviewController **aController) {
+  NS_ADDREF(*aController = mController);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TaskbarPreview::GetTooltip(nsAString &aTooltip) {
+  aTooltip = mTooltip;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TaskbarPreview::SetTooltip(const nsAString &aTooltip) {
+  mTooltip = aTooltip;
+  return CanMakeTaskbarCalls() ? UpdateTooltip() : NS_OK;
+}
+
+NS_IMETHODIMP
+TaskbarPreview::SetVisible(bool visible) {
+  if (mVisible == visible) return NS_OK;
+  mVisible = visible;
+
+  // If the nsWindow has already been destroyed but the caller is still trying
+  // to use it then just pretend that everything succeeded.  The caller doesn't
+  // actually have a way to detect this since it's the same case as when we
+  // CanMakeTaskbarCalls returns false.
+  if (!mWnd)
+    return NS_OK;
+
+  return visible ? Enable() : Disable();
+}
+
+NS_IMETHODIMP
+TaskbarPreview::GetVisible(bool *visible) {
+  *visible = mVisible;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TaskbarPreview::SetActive(bool active) {
+  if (active)
+    sActivePreview = this;
+  else if (sActivePreview == this)
+    sActivePreview = nullptr;
+
+  return CanMakeTaskbarCalls() ? ShowActive(active) : NS_OK;
+}
+
+NS_IMETHODIMP
+TaskbarPreview::GetActive(bool *active) {
+  *active = sActivePreview == this;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TaskbarPreview::Invalidate() {
+  if (!mVisible)
+    return NS_ERROR_FAILURE;
+
+  // DWM Composition is required for previews
+  if (!nsUXThemeData::CheckForCompositor())
+    return NS_OK;
+
+  HWND previewWindow = PreviewWindow();
+  return FAILED(WinUtils::dwmInvalidateIconicBitmapsPtr(previewWindow))
+       ? NS_ERROR_FAILURE
+       : NS_OK;
+}
+
+nsresult
+TaskbarPreview::UpdateTaskbarProperties() {
+  nsresult rv = UpdateTooltip();
+
+  // If we are the active preview and our window is the active window, restore
+  // our active state - otherwise some other non-preview window is now active
+  // and should be displayed as so.
+  if (sActivePreview == this) {
+    if (mWnd == ::GetActiveWindow()) {
+      nsresult rvActive = ShowActive(true);
+      if (NS_FAILED(rvActive))
+        rv = rvActive;
+    } else {
+      sActivePreview = nullptr;
+    }
+  }
+  return rv;
+}
+
+nsresult
+TaskbarPreview::Enable() {
+  nsresult rv = NS_OK;
+  if (CanMakeTaskbarCalls()) {
+    rv = UpdateTaskbarProperties();
+  } else {
+    WindowHook &hook = GetWindowHook();
+    hook.AddMonitor(nsAppShell::GetTaskbarButtonCreatedMessage(), MainWindowHook, this);
+  }
+  return rv;
+}
+
+nsresult
+TaskbarPreview::Disable() {
+  WindowHook &hook = GetWindowHook();
+  (void) hook.RemoveMonitor(nsAppShell::GetTaskbarButtonCreatedMessage(), MainWindowHook, this);
+
+  return NS_OK;
+}
+
+bool
+TaskbarPreview::IsWindowAvailable() const {
+  if (mWnd) {
+    nsWindow* win = WinUtils::GetNSWindowPtr(mWnd);
+    if(win && !win->Destroyed()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+void
+TaskbarPreview::DetachFromNSWindow() {
+  WindowHook &hook = GetWindowHook();
+  hook.RemoveMonitor(WM_DESTROY, MainWindowHook, this);
+  mWnd = nullptr;
+}
+
+LRESULT
+TaskbarPreview::WndProc(UINT nMsg, WPARAM wParam, LPARAM lParam) {
+  switch (nMsg) {
+    case WM_DWMSENDICONICTHUMBNAIL:
+      {
+        uint32_t width = HIWORD(lParam);
+        uint32_t height = LOWORD(lParam);
+        float aspectRatio = width/float(height);
+
+        nsresult rv;
+        float preferredAspectRatio;
+        rv = mController->GetThumbnailAspectRatio(&preferredAspectRatio);
+        if (NS_FAILED(rv))
+          break;
+
+        uint32_t thumbnailWidth = width;
+        uint32_t thumbnailHeight = height;
+
+        if (aspectRatio > preferredAspectRatio) {
+          thumbnailWidth = uint32_t(thumbnailHeight * preferredAspectRatio);
+        } else {
+          thumbnailHeight = uint32_t(thumbnailWidth / preferredAspectRatio);
+        }
+
+        DrawBitmap(thumbnailWidth, thumbnailHeight, false);
+      }
+      break;
+    case WM_DWMSENDICONICLIVEPREVIEWBITMAP:
+      {
+        uint32_t width, height;
+        nsresult rv;
+        rv = mController->GetWidth(&width);
+        if (NS_FAILED(rv))
+          break;
+        rv = mController->GetHeight(&height);
+        if (NS_FAILED(rv))
+          break;
+
+        double scale = nsIWidget::DefaultScaleOverride();
+        if (scale <= 0.0)
+          scale = gfxWindowsPlatform::GetPlatform()->GetDPIScale();
+
+        DrawBitmap(NSToIntRound(scale * width), NSToIntRound(scale * height), true);
+      }
+      break;
+  }
+  return ::DefWindowProcW(PreviewWindow(), nMsg, wParam, lParam);
+}
+
+bool
+TaskbarPreview::CanMakeTaskbarCalls() {
+  // If the nsWindow has already been destroyed and we know it but our caller
+  // clearly doesn't so we can't make any calls.
+  if (!mWnd)
+    return false;
+  // Certain functions like SetTabOrder seem to require a visible window. During
+  // window close, the window seems to be hidden before being destroyed.
+  if (!::IsWindowVisible(mWnd))
+    return false;
+  if (mVisible) {
+    nsWindow *window = WinUtils::GetNSWindowPtr(mWnd);
+    NS_ASSERTION(window, "Could not get nsWindow from HWND");
+    return window->HasTaskbarIconBeenCreated();
+  }
+  return false;
+}
+
+WindowHook&
+TaskbarPreview::GetWindowHook() {
+  nsWindow *window = WinUtils::GetNSWindowPtr(mWnd);
+  NS_ASSERTION(window, "Cannot use taskbar previews in an embedded context!");
+
+  return window->GetWindowHook();
+}
+
+void
+TaskbarPreview::EnableCustomDrawing(HWND aHWND, bool aEnable) {
+  BOOL enabled = aEnable;
+  WinUtils::dwmSetWindowAttributePtr(
+      aHWND,
+      DWMWA_FORCE_ICONIC_REPRESENTATION,
+      &enabled,
+      sizeof(enabled));
+
+  WinUtils::dwmSetWindowAttributePtr(
+      aHWND,
+      DWMWA_HAS_ICONIC_BITMAP,
+      &enabled,
+      sizeof(enabled));
+}
+
+
+nsresult
+TaskbarPreview::UpdateTooltip() {
+  NS_ASSERTION(CanMakeTaskbarCalls() && mVisible, "UpdateTooltip called on invisible tab preview");
+
+  if (FAILED(mTaskbar->SetThumbnailTooltip(PreviewWindow(), mTooltip.get())))
+    return NS_ERROR_FAILURE;
+  return NS_OK;
+}
+
+void
+TaskbarPreview::DrawBitmap(uint32_t width, uint32_t height, bool isPreview) {
+  nsresult rv;
+  nsRefPtr<gfxWindowsSurface> surface = new gfxWindowsSurface(gfxIntSize(width, height), gfxImageFormat::ARGB32);
+
+  nsCOMPtr<nsIDocShell> shell = do_QueryReferent(mDocShell);
+
+  if (!shell)
+    return;
+
+  rv = GetRenderingContext(shell, surface, width, height);
+  if (NS_FAILED(rv))
+    return;
+
+  bool drawFrame = false;
+  if (isPreview)
+    rv = mController->DrawPreview(gCtx, &drawFrame);
+  else
+    rv = mController->DrawThumbnail(gCtx, width, height, &drawFrame);
+
+  if (NS_FAILED(rv))
+    return;
+
+  HDC hDC = surface->GetDC();
+  HBITMAP hBitmap = (HBITMAP)GetCurrentObject(hDC, OBJ_BITMAP);
+
+  DWORD flags = drawFrame ? DWM_SIT_DISPLAYFRAME : 0;
+  POINT pptClient = { 0, 0 };
+  if (isPreview)
+    WinUtils::dwmSetIconicLivePreviewBitmapPtr(PreviewWindow(), hBitmap, &pptClient, flags);
+  else
+    WinUtils::dwmSetIconicThumbnailPtr(PreviewWindow(), hBitmap, flags);
+
+  ResetRenderingContext();
+}
+
+/* static */
+bool
+TaskbarPreview::MainWindowHook(void *aContext,
+                               HWND hWnd, UINT nMsg,
+                               WPARAM wParam, LPARAM lParam,
+                               LRESULT *aResult)
+{
+  NS_ASSERTION(nMsg == nsAppShell::GetTaskbarButtonCreatedMessage() ||
+               nMsg == WM_DESTROY,
+               "Window hook proc called with wrong message");
+  NS_ASSERTION(aContext, "Null context in MainWindowHook");
+  if (!aContext)
+    return false;
+  TaskbarPreview *preview = reinterpret_cast<TaskbarPreview*>(aContext);
+  if (nMsg == WM_DESTROY) {
+    // nsWindow is being destroyed
+    // We can't really do anything at this point including removing hooks
+    preview->mWnd = nullptr;
+  } else {
+    nsWindow *window = WinUtils::GetNSWindowPtr(preview->mWnd);
+    if (window) {
+      window->SetHasTaskbarIconBeenCreated();
+
+      if (preview->mVisible)
+        preview->UpdateTaskbarProperties();
+    }
+  }
+  return false;
+}
+
+TaskbarPreview *
+TaskbarPreview::sActivePreview = nullptr;
+
+} // namespace widget
+} // namespace mozilla
+