Fix BGR/BGRA image use under GLES, auto-convert as needed

Signed-off-by: falkTX <falktx@falktx.com>

dgl/OpenGL.hpp

@@ -249,6 +249,18 @@ public:
     */
     void drawAt(const GraphicsContext& context, const Point<int>& pos) override;
 
+   #ifdef DGL_USE_GLES
+   /**
+      Get the image format.
+    */
+    ImageFormat getFormat() const noexcept;
+
+   /**
+      Get the raw image data.
+    */
+    const char* getRawData() const noexcept;
+   #endif
+
    /**
       TODO document this.
     */
@@ -312,6 +324,10 @@ private:
     bool setupCalled;
     bool textureInit;
     GLuint textureId;
+   #ifdef DGL_USE_GLES
+    mutable char* convertedData;
+    mutable const char* rawDataLast;
+   #endif
 };
 
 // --------------------------------------------------------------------------------------------------------------------

dgl/src/OpenGL.cpp

@@ -37,6 +37,10 @@ OpenGLImage::OpenGLImage()
       setupCalled(false),
       textureInit(false),
       textureId(0)
+   #ifdef DGL_USE_GLES
+    , convertedData(nullptr)
+    , rawDataLast(nullptr)
+    #endif
 {
 }
 
@@ -45,6 +49,10 @@ OpenGLImage::OpenGLImage(const char* const rdata, const uint w, const uint h, co
       setupCalled(false),
       textureInit(true),
       textureId(0)
+   #ifdef DGL_USE_GLES
+    , convertedData(nullptr)
+    , rawDataLast(nullptr)
+    #endif
 {
     glGenTextures(1, &textureId);
     DISTRHO_SAFE_ASSERT(textureId != 0);
@@ -55,6 +63,10 @@ OpenGLImage::OpenGLImage(const char* const rdata, const Size<uint>& s, const Ima
       setupCalled(false),
       textureInit(true),
       textureId(0)
+   #ifdef DGL_USE_GLES
+    , convertedData(nullptr)
+    , rawDataLast(nullptr)
+    #endif
 {
     glGenTextures(1, &textureId);
     DISTRHO_SAFE_ASSERT(textureId != 0);
@@ -65,6 +77,10 @@ OpenGLImage::OpenGLImage(const OpenGLImage& image)
       setupCalled(false),
       textureInit(true),
       textureId(0)
+   #ifdef DGL_USE_GLES
+    , convertedData(nullptr)
+    , rawDataLast(nullptr)
+    #endif
 {
     glGenTextures(1, &textureId);
     DISTRHO_SAFE_ASSERT(textureId != 0);
@@ -74,6 +90,10 @@ OpenGLImage::~OpenGLImage()
 {
     if (textureId != 0)
         glDeleteTextures(1, &textureId);
+
+   #ifdef DGL_USE_GLES
+    std::free(convertedData);
+   #endif
 }
 
 void OpenGLImage::loadFromMemory(const char* const rdata, const Size<uint>& s, const ImageFormat fmt) noexcept
@@ -111,6 +131,10 @@ OpenGLImage::OpenGLImage(const char* const rdata, const uint w, const uint h, co
       setupCalled(false),
       textureInit(true),
       textureId(0)
+   #ifdef DGL_USE_GLES
+    , convertedData(nullptr)
+    , rawDataLast(nullptr)
+    #endif
 {
     glGenTextures(1, &textureId);
     DISTRHO_SAFE_ASSERT(textureId != 0);
@@ -121,6 +145,10 @@ OpenGLImage::OpenGLImage(const char* const rdata, const Size<uint>& s, const GLe
       setupCalled(false),
       textureInit(true),
       textureId(0)
+   #ifdef DGL_USE_GLES
+    , convertedData(nullptr)
+    , rawDataLast(nullptr)
+    #endif
 {
     glGenTextures(1, &textureId);
     DISTRHO_SAFE_ASSERT(textureId != 0);

dgl/src/OpenGL3.cpp

@@ -562,6 +562,70 @@ void OpenGLImage::drawAt(const GraphicsContext& context, const Point<int>& pos)
     glBindTexture(GL_TEXTURE_2D, 0);
 }
 
+#ifdef DGL_USE_GLES
+ImageFormat OpenGLImage::getFormat() const noexcept
+{
+    switch (format)
+    {
+    case kImageFormatBGR:
+        return kImageFormatRGB;
+    case kImageFormatBGRA:
+        return kImageFormatRGBA;
+    default:
+        return format;
+    }
+}
+
+const char* OpenGLImage::getRawData() const noexcept
+{
+    if (rawDataLast != rawData)
+    {
+        if (format == kImageFormatBGR || format == kImageFormatBGRA)
+        {
+            const uint w = size.getWidth();
+            const uint h = size.getHeight();
+
+            std::free(convertedData);
+
+            if (format == kImageFormatBGR)
+            {
+                convertedData = static_cast<char*>(std::malloc(sizeof(char) * 3 * w * h));
+                for (int i = 0; i < w * h; ++i)
+                {
+                    convertedData[i * 3 + 0] = rawData[i * 3 + 2];
+                    convertedData[i * 3 + 1] = rawData[i * 3 + 1];
+                    convertedData[i * 3 + 2] = rawData[i * 3 + 0];
+                }
+            }
+            else
+            {
+                convertedData = static_cast<char*>(std::malloc(sizeof(char) * 4 * w * h));
+                for (int i = 0; i < w * h; ++i)
+                {
+                    convertedData[i * 4 + 0] = rawData[i * 4 + 2];
+                    convertedData[i * 4 + 1] = rawData[i * 4 + 1];
+                    convertedData[i * 4 + 2] = rawData[i * 4 + 0];
+                    convertedData[i * 4 + 3] = rawData[i * 4 + 3];
+                }
+            }
+        }
+        else
+        {
+            std::free(convertedData);
+            convertedData = nullptr;
+        }
+
+        rawDataLast = rawData;
+    }
+
+    return
+     #ifdef DGL_USE_GLES
+      convertedData != nullptr ? convertedData :
+     #endif
+      rawData;
+}
+#endif
+
 #ifdef DGL_ALLOW_DEPRECATED_METHODS
 void OpenGLImage::draw()
 {
@@ -634,6 +698,9 @@ void ImageBaseKnob<OpenGLImage>::onDisplay()
     DISTRHO_SAFE_ASSERT_RETURN(imageFormat != kImageFormatBGR && imageFormat != kImageFormatBGRA,);
    #endif
 
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
     const GLfloat color[4] = { 1.0f, 1.0f, 1.0f, 1.0f };
     glUniform4fv(gl3context.color, 1, color);
 
@@ -748,6 +815,8 @@ void ImageBaseKnob<OpenGLImage>::onDisplay()
     glUniform1i(gl3context.usingTexture, 0);
     glBindBuffer(GL_ARRAY_BUFFER, 0);
     glBindTexture(GL_TEXTURE_2D, 0);
+
+    glDisable(GL_BLEND);
 }
 
 template class ImageBaseKnob<OpenGLImage>;

dgl/src/nanovg/nanovg_gl.h

@@ -834,10 +834,10 @@ static int glnvg__renderCreateTexture(void* uptr, int type, int w, int h, int im
 		tex->data = (uint8_t*)malloc(sizeof(uint8_t) * 4 * w * h);
 		for (int i = 0; i < w * h; ++i)
 		{
-			tex->data[i*3+0] = data[i*3+3];
-			tex->data[i*3+1] = data[i*3+2];
-			tex->data[i*3+2] = data[i*3+1];
-			tex->data[i*3+3] = data[i*3+0];
+			tex->data[i*4+0] = data[i*4+2];
+			tex->data[i*4+1] = data[i*4+1];
+			tex->data[i*4+2] = data[i*4+0];
+			tex->data[i*4+3] = data[i*4+3];
 		}
 		data = tex->data;
 		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);