Added functions to draw images at sub-pixel positions

This can be used for smoother mouse cursor movement when rendering our
own mouse cursor (already changed in this commit) and is also necessary
for implementing support for HiDPI font rendering.

Also dropped some almost duplicated OpenGL code.

1 files changed, 20 insertions, 106 deletions

diff --git a/src/openglgraphics.cpp b/src/openglgraphics.cpp
index ea37bdaa..9e77e5f7 100644
--- a/src/openglgraphics.cpp
+++ b/src/openglgraphics.cpp
@@ -153,71 +153,11 @@ void OpenGLGraphics::updateSize(int windowWidth, int windowHeight, float scale)
     glOrtho(0.0, (double)mWidth, (double)mHeight, 0.0, -1.0, 1.0);
 }
 
-static inline void drawQuad(Image *image,
-                            int srcX, int srcY, int dstX, int dstY,
-                            int width, int height)
-{
-    if (Image::getTextureType() == GL_TEXTURE_2D)
-    {
-        // Find OpenGL normalized texture coordinates.
-        const float texX1 = static_cast<float>(srcX) /
-                            static_cast<float>(image->getTextureWidth());
-        const float texY1 = static_cast<float>(srcY) /
-                            static_cast<float>(image->getTextureHeight());
-        const float texX2 = static_cast<float>(srcX + width) /
-                            static_cast<float>(image->getTextureWidth());
-        const float texY2 = static_cast<float>(srcY + height) /
-                            static_cast<float>(image->getTextureHeight());
-
-        GLfloat tex[] =
-        {
-            texX1, texY1,
-            texX2, texY1,
-            texX2, texY2,
-            texX1, texY2
-        };
-
-        GLint vert[] =
-        {
-            dstX, dstY,
-            dstX + width, dstY,
-            dstX + width, dstY + height,
-            dstX, dstY + height
-        };
-
-        glVertexPointer(2, GL_INT, 0, &vert);
-        glTexCoordPointer(2, GL_FLOAT, 0, &tex);
-
-        glDrawArrays(GL_QUADS, 0, 4);
-    }
-    else
-    {
-        GLint tex[] =
-        {
-            srcX, srcY,
-            srcX + width, srcY,
-            srcX + width, srcY + height,
-            srcX, srcY + height
-        };
-        GLint vert[] =
-        {
-            dstX, dstY,
-            dstX + width, dstY,
-            dstX + width, dstY + height,
-            dstX, dstY + height
-        };
-
-        glVertexPointer(2, GL_INT, 0, &vert);
-        glTexCoordPointer(2, GL_INT, 0, &tex);
-
-        glDrawArrays(GL_QUADS, 0, 4);
-    }
-}
-
 static inline void drawRescaledQuad(Image *image,
-                                    int srcX, int srcY, int dstX, int dstY,
+                                    int srcX, int srcY,
+                                    float dstX, float dstY,
                                     int width, int height,
-                                    int desiredWidth, int desiredHeight)
+                                    float desiredWidth, float desiredHeight)
 {
     if (Image::getTextureType() == GL_TEXTURE_2D)
     {
@@ -231,7 +171,7 @@ static inline void drawRescaledQuad(Image *image,
         const float texY2 = static_cast<float>(srcY + height) /
                             static_cast<float>(image->getTextureHeight());
 
-        GLfloat tex[] =
+        const GLfloat tex[] =
         {
             texX1, texY1,
             texX2, texY1,
@@ -239,7 +179,7 @@ static inline void drawRescaledQuad(Image *image,
             texX1, texY2
         };
 
-        GLint vert[] =
+        const GLfloat vert[] =
         {
             dstX, dstY,
             dstX + desiredWidth, dstY,
@@ -247,21 +187,21 @@ static inline void drawRescaledQuad(Image *image,
             dstX, dstY + desiredHeight
         };
 
-        glVertexPointer(2, GL_INT, 0, &vert);
+        glVertexPointer(2, GL_FLOAT, 0, &vert);
         glTexCoordPointer(2, GL_FLOAT, 0, &tex);
 
         glDrawArrays(GL_QUADS, 0, 4);
     }
     else
     {
-        GLint tex[] =
+        const GLint tex[] =
         {
             srcX, srcY,
             srcX + width, srcY,
             srcX + width, srcY + height,
             srcX, srcY + height
         };
-        GLint vert[] =
+        const GLfloat vert[] =
         {
             dstX, dstY,
             dstX + desiredWidth, dstY,
@@ -269,7 +209,7 @@ static inline void drawRescaledQuad(Image *image,
             dstX, dstY + desiredHeight
         };
 
-        glVertexPointer(2, GL_INT, 0, &vert);
+        glVertexPointer(2, GL_FLOAT, 0, &vert);
         glTexCoordPointer(2, GL_INT, 0, &tex);
 
         glDrawArrays(GL_QUADS, 0, 4);
@@ -277,52 +217,26 @@ static inline void drawRescaledQuad(Image *image,
 }
 
 
-bool OpenGLGraphics::drawImage(Image *image, int srcX, int srcY,
-                               int dstX, int dstY,
-                               int width, int height, bool useColor)
-{
-    if (!image)
-        return false;
-
-    srcX += image->mBounds.x;
-    srcY += image->mBounds.y;
-
-    if (!useColor)
-        glColor4f(1.0f, 1.0f, 1.0f, image->mAlpha);
-
-    bindTexture(Image::mTextureType, image->mGLImage);
-
-    setTexturingAndBlending(true);
-
-    drawQuad(image, srcX, srcY, dstX, dstY, width, height);
-
-    if (!useColor)
-    {
-        glColor4ub(static_cast<GLubyte>(mColor.r),
-                   static_cast<GLubyte>(mColor.g),
-                   static_cast<GLubyte>(mColor.b),
-                   static_cast<GLubyte>(mColor.a));
-    }
-
-    return true;
-}
-
 bool OpenGLGraphics::drawRescaledImage(Image *image, int srcX, int srcY,
                                        int dstX, int dstY,
                                        int width, int height,
                                        int desiredWidth, int desiredHeight,
                                        bool useColor)
 {
+    return drawRescaledImageF(image, srcX, srcY, dstX, dstY,
+                              width, height, desiredWidth, desiredHeight,
+                              useColor);
+}
+
+bool OpenGLGraphics::drawRescaledImageF(Image *image, int srcX, int srcY,
+                                        float dstX, float dstY,
+                                        int width, int height,
+                                        float desiredWidth, float desiredHeight,
+                                        bool useColor)
+{
     if (!image)
         return false;
 
-    // Just draw the image normally when no resizing is necessary,
-    if (width == desiredWidth && height == desiredHeight)
-    {
-        return drawImage(image, srcX, srcY, dstX, dstY,
-                         width, height, useColor);
-    }
-
     srcX += image->mBounds.x;
     srcY += image->mBounds.y;