Add support to webp encoded dragged images

src/app/CMakeLists.txt

@@ -105,6 +105,13 @@ else()
   target_sources(app-lib PRIVATE font_path_unix.cpp)
 endif()
 
+# This defines a specific webp decoding utility function for using
+# in Windows when dragging and dropping images that are stored as
+# webp files (like Chrome does).
+if(WIN32 AND ENABLE_WEBP)
+  target_sources(app-lib PRIVATE util/decode_webp.cpp)
+endif()
+
 # Trial-version vs Full version (enable save command)
 if(ENABLE_TRIAL_MODE)
   target_compile_definitions(app-lib PUBLIC -DENABLE_TRIAL_MODE)

src/app/cmd/drop_on_timeline.cpp

@@ -23,6 +23,10 @@
 #include "doc/layer_list.h"
 #include "render/dithering.h"
 
+#if ENABLE_WEBP && LAF_WINDOWS
+#include "app/util/decode_webp.h"
+#endif
+
 #include <algorithm>
 
 namespace app {

src/app/util/decode_webp.cpp

@@ -0,0 +1,81 @@
+// Aseprite
+// Copyright (C) 2024  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#include "app/util/decode_webp.h"
+
+#include <webp/demux.h>
+#include <webp/mux.h>
+
+namespace app {
+namespace util {
+
+os::SurfaceRef decode_webp(const uint8_t* buf, uint32_t len)
+{
+  // I've considered using the FileFormatsManager here but we don't have a file
+  // in this case just the bytes. At some point maye we should refactor this or
+  // the WepFormat class to avoid duplicated logic.
+  WebPData webp_data;
+  WebPDataInit(&webp_data);
+  webp_data.bytes = &buf[0];
+  webp_data.size = len;
+
+  WebPAnimDecoderOptions dec_options;
+  WebPAnimDecoderOptionsInit(&dec_options);
+  dec_options.color_mode = MODE_RGBA;
+
+  WebPAnimDecoder* dec = WebPAnimDecoderNew(&webp_data, &dec_options);
+  if (dec == nullptr) {
+    // Error parsing WebP image
+    return nullptr;
+  }
+
+  WebPAnimInfo anim_info;
+  if (!WebPAnimDecoderGetInfo(dec, &anim_info)) {
+    // Error getting global info about the WebP animation
+    return nullptr;
+  }
+
+  WebPDecoderConfig config;
+  WebPInitDecoderConfig(&config);
+  if (WebPGetFeatures(webp_data.bytes, webp_data.size, &config.input)) {
+
+  }
+  else {
+    config.input.has_alpha = false;
+  }
+
+  const int w = anim_info.canvas_width;
+  const int h = anim_info.canvas_height;
+
+  if (anim_info.frame_count <= 0)
+    return nullptr;
+
+  auto surface = os::instance()->makeSurface(w, h);
+
+  // We just want the first frame, so we don't iterate.
+  WebPAnimDecoderHasMoreFrames(dec);
+
+  uint8_t* frame_rgba;
+  int frame_timestamp = 0;
+  if (!WebPAnimDecoderGetNext(dec, &frame_rgba, &frame_timestamp)) {
+    // Error loading WebP frame
+    return nullptr;
+  }
+
+  const uint32_t* src = (const uint32_t*)frame_rgba;
+  for (int y = 0; y < h; ++y, src += w) {
+    memcpy(surface->getData(0, y), src, w * sizeof(uint32_t));
+  }
+
+  WebPAnimDecoderReset(dec);
+
+  WebPAnimDecoderDelete(dec);
+
+  return surface;
+}
+
+}  // namespace util
+}  // namespace app

src/app/util/decode_webp.h

@@ -0,0 +1,31 @@
+// Aseprite
+// Copyright (C) 2024  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_UTIL_DECODE_WEBP_H_INCLUDED
+#define APP_UTIL_DECODE_WEBP_H_INCLUDED
+#pragma once
+
+#include "os/surface.h"
+#include "os/system.h"
+
+namespace app {
+
+namespace util {
+
+// Decodes webp content passed in buf and returns a surface with just the first
+// frame.
+os::SurfaceRef decode_webp(const uint8_t* buf, uint32_t len);
+
+static void* once = []() {
+  os::set_decode_webp(decode_webp);
+  return nullptr;
+}();
+
+}
+
+}
+
+#endif