1 files changed, 239 insertions, 0 deletions
diff --git a/vcl/opengl/shaders/areaScaleFragmentShader.glsl b/vcl/opengl/shaders/areaScaleFragmentShader.glsl
new file mode 100644
index 000000000..5dab5ba01
--- /dev/null
+++ b/vcl/opengl/shaders/areaScaleFragmentShader.glsl
@@ -0,0 +1,239 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#version 130
+
+uniform sampler2D sampler;
+uniform int swidth;
+uniform int sheight;
+uniform float xscale;
+uniform float yscale;
+uniform float xoffset;
+uniform float yoffset;
+uniform float xfrompixelratio;
+uniform float yfrompixelratio;
+uniform float xtopixelratio;
+uniform float ytopixelratio;
+
+varying vec2 tex_coord;
+
+// This mode makes the scaling work like maskedTextureFragmentShader.glsl
+// (instead of like plain textureVertexShader.glsl).
+#ifdef MASKED
+varying vec2 mask_coord;
+uniform sampler2D mask;
+#endif
+
+#ifdef USE_REDUCED_REGISTER_VARIANT
+
+vec4 getTexel(int x, int y)
+{
+    vec2 pos = vec2( x * xfrompixelratio + xoffset, y * yfrompixelratio + yoffset );
+    vec4 texel = texture2D(sampler, pos);
+#ifdef MASKED
+    texel.a = 1.0 - texture2D(mask, pos - tex_coord.st + mask_coord.st).r;
+#endif
+    return texel;
+}
+
+void main(void)
+{
+    // Convert to pixel coordinates again.
+    int dx = int(( tex_coord.s - xoffset ) * xtopixelratio );
+    int dy = int(( tex_coord.t - yoffset ) * ytopixelratio );
+
+    // Compute the range of source pixels which will make up this destination pixel.
+    float fsx1 = min(dx * xscale,   float(swidth - 1));
+    float fsx2 = min(fsx1 + xscale, float(swidth - 1));
+
+    float fsy1 = min(dy * yscale,   float(sheight - 1));
+    float fsy2 = min(fsy1 + yscale, float(sheight - 1));
+
+    // To whole pixel coordinates.
+    int xstart = int(floor(fsx1));
+    int xend   = int(floor(fsx2));
+
+    int ystart = int(floor(fsy1));
+    int yend   = int(floor(fsy2));
+
+    float xlength = fsx2 - fsx1;
+    float ylength = fsy2 - fsy1;
+
+    float xContribution[3];
+    xContribution[0] = (1.0 - max(0.0, fsx1 - xstart))     / xlength;
+    xContribution[1] =  1.0 / xlength;
+    xContribution[2] = (1.0 - max(0.0, (xend + 1) - fsx2)) / xlength;
+
+    float yContribution[3];
+    yContribution[0] = (1.0 - max(0.0, fsy1 - ystart))     / ylength;
+    yContribution[1] =  1.0 / ylength;
+    yContribution[2] = (1.0 - max(0.0, (yend + 1) - fsy2)) / ylength;
+
+    vec4 sumAll = vec4(0.0, 0.0, 0.0, 0.0);
+    vec4 texel;
+    // First Y pass
+    {
+        vec4 sumX = vec4(0.0, 0.0, 0.0, 0.0);
+
+        sumX += getTexel(xstart, ystart) * xContribution[0];
+        for (int x = xstart + 1; x < xend; ++x)
+        {
+           sumX += getTexel(x, ystart) * xContribution[1];
+        }
+        sumX += getTexel(xend, ystart) * xContribution[2];
+
+        sumAll += sumX * yContribution[0];
+    }
+
+    // Middle Y Passes
+    for (int y = ystart + 1; y < yend; ++y)
+    {
+        vec4 sumX = vec4(0.0, 0.0, 0.0, 0.0);
+
+        sumX += getTexel(xstart, y) * xContribution[0];
+        for (int x = xstart + 1; x < xend; ++x)
+        {
+            sumX += getTexel(x, y) * xContribution[1];
+        }
+        sumX += getTexel(xend, y) * xContribution[2];
+
+        sumAll += sumX * yContribution[1];
+    }
+
+    // Last Y pass
+    {
+        vec4 sumX = vec4(0.0, 0.0, 0.0, 0.0);
+
+        sumX += getTexel(xstart, yend) * xContribution[0];
+        for (int x = xstart + 1; x < xend; ++x)
+        {
+            sumX += getTexel(x, yend) * xContribution[1];
+        }
+        sumX += getTexel(xend, yend) * xContribution[2];
+
+        sumAll += sumX * yContribution[2];
+    }
+
+    gl_FragColor = sumAll;
+}
+#else
+void main(void)
+{
+    // Convert to pixel coordinates again.
+    int dx = int(( tex_coord.s - xoffset ) * xtopixelratio );
+    int dy = int(( tex_coord.t - yoffset ) * ytopixelratio );
+
+    // How much each column/row will contribute to the resulting pixel.
+    // Note: These values are always the same for the same X (or Y),
+    // so they could be precalculated in C++ and passed to the shader,
+    // but GLSL has limits on the size of uniforms passed to it,
+    // so it'd need something like texture buffer objects from newer
+    // GLSL versions, and it seems the hassle is not really worth it.
+    float xratio[ 16 + 2 ];
+    float yratio[ 16 + 2 ];
+
+    // For finding the first and last source pixel.
+    int xpixel[ 16 + 2 ];
+    int ypixel[ 16 + 2 ];
+
+    int xpos = 0;
+    int ypos = 0;
+
+    // Compute the range of source pixels which will make up this destination pixel.
+    float fsx1 = dx * xscale;
+    float fsx2 = fsx1 + xscale;
+    // To whole pixel coordinates.
+    int sx1 = int( ceil( fsx1 ) );
+    int sx2 = int( floor( fsx2 ) );
+    // Range checking.
+    sx2 = min( sx2, swidth - 1 );
+    sx1 = min( sx1, sx2 );
+
+    // How much one full column contributes to the resulting pixel.
+    float width = min( xscale, swidth - fsx1 );
+
+    if( sx1 - fsx1 > 0.001 )
+    {   // The first column contributes only partially.
+        xpixel[ xpos ] = sx1 - 1;
+        xratio[ xpos ] = ( sx1 - fsx1 ) / width;
+        ++xpos;
+    }
+    for( int sx = sx1; sx < sx2; ++sx )
+    {   // Columns that fully contribute to the resulting pixel.
+        xpixel[ xpos ] = sx;
+        xratio[ xpos ] = 1.0 / width;
+        ++xpos;
+    }
+    if( fsx2 - sx2 > 0.001 )
+    {   // The last column contributes only partially.
+        xpixel[ xpos ] = sx2;
+        xratio[ xpos ] = min( min( fsx2 - sx2, 1.0 ) / width, 1.0 );
+        ++xpos;
+    }
+
+    // The same for Y.
+    float fsy1 = dy * yscale;
+    float fsy2 = fsy1 + yscale;
+    int sy1 = int( ceil( fsy1 ) );
+    int sy2 = int( floor( fsy2 ) );
+    sy2 = min( sy2, sheight - 1 );
+    sy1 = min( sy1, sy2 );
+
+    float height = min( yscale, sheight - fsy1 );
+
+    if( sy1 - fsy1 > 0.001 )
+    {
+        ypixel[ ypos ] = sy1 - 1;
+        yratio[ ypos ] = ( sy1 - fsy1 ) / height;
+        ++ypos;
+    }
+    for( int sy = sy1; sy < sy2; ++sy )
+    {
+        ypixel[ ypos ] = sy;
+        yratio[ ypos ] = 1.0 / height;
+        ++ypos;
+    }
+    if( fsy2 - sy2 > 0.001 )
+    {
+        ypixel[ ypos ] = sy2;
+        yratio[ ypos ] = min( min( fsy2 - sy2, 1.0 ) / height, 1.0 );
+        ++ypos;
+    }
+
+    int xstart = xpixel[ 0 ];
+    int xend = xpixel[ xpos - 1 ];
+    int ystart = ypixel[ 0 ];
+    int yend = ypixel[ ypos - 1 ];
+
+    vec4 sum = vec4( 0.0, 0.0, 0.0, 0.0 );
+
+    ypos = 0;
+    for( int y = ystart; y <= yend; ++y, ++ypos )
+    {
+        vec4 tmp = vec4( 0.0, 0.0, 0.0, 0.0 );
+        xpos = 0;
+        for( int x = xstart; x <= xend; ++x, ++xpos )
+        {
+            vec2 pos = vec2( x * xfrompixelratio + xoffset, y * yfrompixelratio + yoffset );
+#ifndef MASKED
+            tmp += texture2D( sampler, pos ) * xratio[ xpos ];
+#else
+            vec4 texel;
+            texel = texture2D( sampler, pos );
+            texel.a = 1.0 - texture2D( mask, pos - tex_coord.st + mask_coord.st ).r;
+            tmp += texel * xratio[ xpos ];
+#endif
+        }
+        sum += tmp * yratio[ ypos ];
+    }
+
+    gl_FragColor = sum;
+}
+#endif
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */