From d22bb9276454937aa19a9bc867839e02434b0c30 Mon Sep 17 00:00:00 2001
From: Peter Nelson <peter@peterdn.com>
Date: Sun, 3 May 2020 17:12:54 +0100
Subject: [PATCH] LibGfx: Add support for animated images to
 ImageDecoder{Plugin}

Adds methods to determine whether an image is animated, how many times
the animation loops, the number of frames, and to get individual frames.

Implements stubs of these methods for PNGImageDecoderPlugin and
GIFImageDecoderPlugin.
---
 Libraries/LibGfx/GIFLoader.cpp  | 24 ++++++++++++++++++++++++
 Libraries/LibGfx/GIFLoader.h    |  4 ++++
 Libraries/LibGfx/ImageDecoder.h | 18 ++++++++++++++++--
 Libraries/LibGfx/PNGLoader.cpp  | 23 +++++++++++++++++++++++
 Libraries/LibGfx/PNGLoader.h    |  4 ++++
 5 files changed, 71 insertions(+), 2 deletions(-)

diff --git a/Libraries/LibGfx/GIFLoader.cpp b/Libraries/LibGfx/GIFLoader.cpp
index df792891dc..559946cc77 100644
--- a/Libraries/LibGfx/GIFLoader.cpp
+++ b/Libraries/LibGfx/GIFLoader.cpp
@@ -528,4 +528,28 @@ bool GIFImageDecoderPlugin::sniff()
     BufferStream stream(buffer);
     return decode_gif_header(stream).has_value();
 }
+
+bool GIFImageDecoderPlugin::is_animated()
+{
+    return false;
+}
+
+size_t GIFImageDecoderPlugin::loop_count()
+{
+    return 0;
+}
+
+size_t GIFImageDecoderPlugin::frame_count()
+{
+    return 1;
+}
+
+ImageFrameDescriptor GIFImageDecoderPlugin::frame(size_t i)
+{
+    if (i > 0) {
+        return { bitmap(), 0 };
+    }
+    return {};
+}
+
 }
diff --git a/Libraries/LibGfx/GIFLoader.h b/Libraries/LibGfx/GIFLoader.h
index b6599e4b7b..b76b131d19 100644
--- a/Libraries/LibGfx/GIFLoader.h
+++ b/Libraries/LibGfx/GIFLoader.h
@@ -46,6 +46,10 @@ public:
     virtual void set_volatile() override;
     [[nodiscard]] virtual bool set_nonvolatile() override;
     virtual bool sniff() override;
+    virtual bool is_animated() override;
+    virtual size_t loop_count() override;
+    virtual size_t frame_count() override;
+    virtual ImageFrameDescriptor frame(size_t i) override;
 
 private:
     OwnPtr<GIFLoadingContext> m_context;
diff --git a/Libraries/LibGfx/ImageDecoder.h b/Libraries/LibGfx/ImageDecoder.h
index f300cb4871..bcc08c675c 100644
--- a/Libraries/LibGfx/ImageDecoder.h
+++ b/Libraries/LibGfx/ImageDecoder.h
@@ -26,15 +26,20 @@
 
 #pragma once
 
-#include <AK/NonnullRefPtr.h>
 #include <AK/OwnPtr.h>
 #include <AK/RefCounted.h>
+#include <AK/RefPtr.h>
 #include <LibGfx/Size.h>
 
 namespace Gfx {
 
 class Bitmap;
 
+struct ImageFrameDescriptor {
+    RefPtr<Bitmap> image;
+    int duration { 0 };
+};
+
 class ImageDecoderPlugin {
 public:
     virtual ~ImageDecoderPlugin() {}
@@ -47,6 +52,11 @@ public:
 
     virtual bool sniff() = 0;
 
+    virtual bool is_animated() = 0;
+    virtual size_t loop_count() = 0;
+    virtual size_t frame_count() = 0;
+    virtual ImageFrameDescriptor frame(size_t i) = 0;
+
 protected:
     ImageDecoderPlugin() {}
 };
@@ -62,7 +72,11 @@ public:
     RefPtr<Gfx::Bitmap> bitmap() const;
     void set_volatile() { m_plugin->set_volatile(); }
     [[nodiscard]] bool set_nonvolatile() { return m_plugin->set_nonvolatile(); }
-    bool sniff() { return m_plugin->sniff(); };
+    bool sniff() const { return m_plugin->sniff(); }
+    bool is_animated() const { return m_plugin->is_animated(); }
+    size_t loop_count() const { return m_plugin->loop_count(); }
+    size_t frame_count() const { return m_plugin->frame_count(); }
+    ImageFrameDescriptor frame(size_t i) const { return m_plugin->frame(i); }
 
 private:
     ImageDecoder(const u8*, size_t);
diff --git a/Libraries/LibGfx/PNGLoader.cpp b/Libraries/LibGfx/PNGLoader.cpp
index 78a3b5a73a..ca7d5136b4 100644
--- a/Libraries/LibGfx/PNGLoader.cpp
+++ b/Libraries/LibGfx/PNGLoader.cpp
@@ -834,4 +834,27 @@ bool PNGImageDecoderPlugin::sniff()
     return decode_png_header(*m_context);
 }
 
+bool PNGImageDecoderPlugin::is_animated()
+{
+    return false;
+}
+
+size_t PNGImageDecoderPlugin::loop_count()
+{
+    return 0;
+}
+
+size_t PNGImageDecoderPlugin::frame_count()
+{
+    return 1;
+}
+
+ImageFrameDescriptor PNGImageDecoderPlugin::frame(size_t i)
+{
+    if (i > 0) {
+        return { bitmap(), 0 };
+    }
+    return {};
+}
+
 }
diff --git a/Libraries/LibGfx/PNGLoader.h b/Libraries/LibGfx/PNGLoader.h
index 7403cdeba5..d6820b931d 100644
--- a/Libraries/LibGfx/PNGLoader.h
+++ b/Libraries/LibGfx/PNGLoader.h
@@ -46,6 +46,10 @@ public:
     virtual void set_volatile() override;
     [[nodiscard]] virtual bool set_nonvolatile() override;
     virtual bool sniff() override;
+    virtual bool is_animated() override;
+    virtual size_t loop_count() override;
+    virtual size_t frame_count() override;
+    virtual ImageFrameDescriptor frame(size_t i) override;
 
 private:
     OwnPtr<PNGLoadingContext> m_context;