From e1d92dff19ceda103a86cdea5333e1c97fa21c97 Mon Sep 17 00:00:00 2001
From: falkTX <falktx@falktx.com>
Date: Sun, 15 Oct 2023 14:59:24 +0200
Subject: [PATCH] Correct CairoImage::loadFromMemory

Signed-off-by: falkTX <falktx@falktx.com>
---
 dgl/src/Cairo.cpp | 57 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 21 deletions(-)

diff --git a/dgl/src/Cairo.cpp b/dgl/src/Cairo.cpp
index d913c4e8..6f31d5f6 100644
--- a/dgl/src/Cairo.cpp
+++ b/dgl/src/Cairo.cpp
@@ -375,11 +375,13 @@ CairoImage::~CairoImage()
 void CairoImage::loadFromMemory(const char* const rdata, const Size<uint>& s, const ImageFormat fmt) noexcept
 {
     const cairo_format_t cairoformat = asCairoImageFormat(fmt);
+    DISTRHO_SAFE_ASSERT_RETURN(cairoformat != CAIRO_FORMAT_INVALID,);
+
     const int width  = static_cast<int>(s.getWidth());
     const int height = static_cast<int>(s.getHeight());
     const int stride = cairo_format_stride_for_width(cairoformat, width);
 
-    uchar* const newdata = (uchar*)std::malloc(static_cast<size_t>(width * height * stride * 4));
+    uchar* const newdata = static_cast<uchar*>(std::malloc(static_cast<size_t>(width * height * stride * 4)));
     DISTRHO_SAFE_ASSERT_RETURN(newdata != nullptr,);
 
     cairo_surface_t* const newsurface = cairo_image_surface_create_for_data(newdata, cairoformat, width, height, stride);
@@ -392,12 +394,14 @@ void CairoImage::loadFromMemory(const char* const rdata, const Size<uint>& s, co
     if (datarefcount != nullptr && --(*datarefcount) == 0)
         std::free(surfacedata);
     else
-        datarefcount = (int*)malloc(sizeof(*datarefcount));
+        datarefcount = static_cast<int*>(std::malloc(sizeof(int)));
 
     surface = newsurface;
     surfacedata = newdata;
     *datarefcount = 1;
 
+    const uchar* const urdata = reinterpret_cast<const uchar*>(rdata);
+
     switch (fmt)
     {
     case kImageFormatNull:
@@ -412,42 +416,53 @@ void CairoImage::loadFromMemory(const char* const rdata, const Size<uint>& s, co
         {
             for (int w = 0; w < width; ++w)
             {
-                newdata[h*width*4+w*4+0] = static_cast<uchar>(rdata[h*width*3+w*3+0]);
-                newdata[h*width*4+w*4+1] = static_cast<uchar>(rdata[h*width*3+w*3+1]);
-                newdata[h*width*4+w*4+2] = static_cast<uchar>(rdata[h*width*3+w*3+2]);
+                newdata[h*width*4+w*4+0] = urdata[h*width*3+w*3+0];
+                newdata[h*width*4+w*4+1] = urdata[h*width*3+w*3+1];
+                newdata[h*width*4+w*4+2] = urdata[h*width*3+w*3+2];
                 newdata[h*width*4+w*4+3] = 0;
             }
         }
         break;
     case kImageFormatBGRA:
         // BGRA8 to CAIRO_FORMAT_ARGB32
-        // FIXME something is wrong here...
-        for (int h = 0, t; h < height; ++h)
+        for (int h = 0; h < height; ++h)
         {
             for (int w = 0; w < width; ++w)
             {
-                if ((t = rdata[h*width*4+w*4+3]) != 0)
-                {
-                    newdata[h*width*4+w*4+0] = static_cast<uchar>(rdata[h*width*4+w*4+0]);
-                    newdata[h*width*4+w*4+1] = static_cast<uchar>(rdata[h*width*4+w*4+1]);
-                    newdata[h*width*4+w*4+2] = static_cast<uchar>(rdata[h*width*4+w*4+2]);
-                    newdata[h*width*4+w*4+3] = static_cast<uchar>(t);
-                }
-                else
-                {
-                    // make all pixels zero, cairo does not render full transparency otherwise
-                    memset(&newdata[h*width*4+w*4], 0, 4);
-                }
+                const uchar a = urdata[h*width*4+w*4+3];
+                newdata[h*width*4+w*4+0] = (urdata[h*width*4+w*4+0] * a) >> 8;
+                newdata[h*width*4+w*4+1] = (urdata[h*width*4+w*4+1] * a) >> 8;
+                newdata[h*width*4+w*4+2] = (urdata[h*width*4+w*4+2] * a) >> 8;
+                newdata[h*width*4+w*4+3] = a;
             }
         }
         break;
     case kImageFormatRGB:
         // RGB8 to CAIRO_FORMAT_RGB24
-        // TODO
+        for (int h = 0; h < height; ++h)
+        {
+            for (int w = 0; w < width; ++w)
+            {
+                newdata[h*width*4+w*4+0] = urdata[h*width*3+w*3+2];
+                newdata[h*width*4+w*4+1] = urdata[h*width*3+w*3+1];
+                newdata[h*width*4+w*4+2] = urdata[h*width*3+w*3+0];
+                newdata[h*width*4+w*4+3] = 0;
+            }
+        }
         break;
     case kImageFormatRGBA:
         // RGBA8 to CAIRO_FORMAT_ARGB32
-        // TODO
+        for (int h = 0; h < height; ++h)
+        {
+            for (int w = 0; w < width; ++w)
+            {
+                const uchar a = urdata[h*width*4+w*4+3];
+                newdata[h*width*4+w*4+0] = (urdata[h*width*4+w*4+2] * a) >> 8;
+                newdata[h*width*4+w*4+1] = (urdata[h*width*4+w*4+1] * a) >> 8;
+                newdata[h*width*4+w*4+2] = (urdata[h*width*4+w*4+0] * a) >> 8;
+                newdata[h*width*4+w*4+3] = a;
+            }
+        }
         break;
     }