PrintTargetRecording.cpp (3953B)
1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- 2 * This Source Code Form is subject to the terms of the Mozilla Public 3 * License, v. 2.0. If a copy of the MPL was not distributed with this 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 5 6 #include "PrintTargetRecording.h" 7 8 #include "cairo.h" 9 #include "mozilla/gfx/2D.h" 10 #include "mozilla/gfx/Logging.h" 11 12 namespace mozilla { 13 namespace gfx { 14 15 PrintTargetRecording::PrintTargetRecording(cairo_surface_t* aCairoSurface, 16 const IntSize& aSize) 17 : PrintTarget(aCairoSurface, aSize) {} 18 19 /* static */ 20 already_AddRefed<PrintTargetRecording> PrintTargetRecording::CreateOrNull( 21 const IntSize& aSize) { 22 if (!Factory::CheckSurfaceSize(aSize)) { 23 return nullptr; 24 } 25 26 // Perhaps surprisingly, this surface is never actually drawn to. This class 27 // creates a DrawTargetRecording using CreateRecordingDrawTarget, and 28 // that needs another DrawTarget to be passed to it. You might expect the 29 // type of the DrawTarget that is passed to matter because it would seem 30 // logical to encoded its type in the recording, and on replaying the 31 // recording a DrawTarget of the same type would be created. However, the 32 // passed DrawTarget's type doesn't seem to be encoded any more accurately 33 // than just "BackendType::CAIRO". Even if it were, the code that replays the 34 // recording is PrintTranslator::TranslateRecording which (indirectly) calls 35 // MakePrintTarget on the type of nsIDeviceContextSpecProxy that is created 36 // for the platform that we're running on, and the type of DrawTarget that 37 // that returns is hardcoded. 38 // 39 // The only reason that we use cairo_recording_surface_create here is: 40 // 41 // * It's pretty much the only cairo_*_surface_create methods that's both 42 // available on all platforms and doesn't require allocating a 43 // potentially large surface. 44 // 45 // * Since we need a DrawTarget to pass to CreateRecordingDrawTarget we 46 // might as well leverage our base class's machinery to create a 47 // DrawTarget (it's as good a way as any other that will work), and to do 48 // that we need a cairo_surface_t. 49 // 50 // So the fact that this is a "recording" PrintTarget and the function that 51 // we call here is cairo_recording_surface_create is simply a coincidence. We 52 // could use any cairo_*_surface_create method and this class would still 53 // work. 54 // 55 cairo_surface_t* surface = 56 cairo_recording_surface_create(CAIRO_CONTENT_COLOR_ALPHA, nullptr); 57 58 if (cairo_surface_status(surface)) { 59 return nullptr; 60 } 61 62 // The new object takes ownership of our surface reference. 63 RefPtr<PrintTargetRecording> target = 64 new PrintTargetRecording(surface, aSize); 65 66 return target.forget(); 67 } 68 69 already_AddRefed<DrawTarget> PrintTargetRecording::MakeDrawTarget( 70 const IntSize& aSize, DrawEventRecorder* aRecorder) { 71 MOZ_ASSERT(aRecorder, "A DrawEventRecorder is required"); 72 73 if (!aRecorder) { 74 return nullptr; 75 } 76 77 RefPtr<DrawTarget> dt = PrintTarget::MakeDrawTarget(aSize, nullptr); 78 if (dt) { 79 dt = CreateRecordingDrawTarget(aRecorder, dt); 80 if (!dt || !dt->IsValid()) { 81 return nullptr; 82 } 83 } 84 85 return dt.forget(); 86 } 87 88 already_AddRefed<DrawTarget> PrintTargetRecording::CreateRecordingDrawTarget( 89 DrawEventRecorder* aRecorder, DrawTarget* aDrawTarget) { 90 MOZ_ASSERT(aRecorder); 91 MOZ_ASSERT(aDrawTarget); 92 93 RefPtr<DrawTarget> dt; 94 95 if (aRecorder) { 96 // It doesn't really matter what we pass as the DrawTarget here. 97 dt = gfx::Factory::CreateRecordingDrawTarget(aRecorder, aDrawTarget, 98 aDrawTarget->GetRect()); 99 } 100 101 if (!dt || !dt->IsValid()) { 102 gfxCriticalNote 103 << "Failed to create a recording DrawTarget for PrintTarget"; 104 return nullptr; 105 } 106 107 return dt.forget(); 108 } 109 110 } // namespace gfx 111 } // namespace mozilla