vcl: Implement bitmap color replacement operation in OpenGL backend

Change-Id: Ia86b67e92985eeb4fb2a5f6cd74c65fab2ac5566

3 files changed, 71 insertions, 2 deletions

diff --git a/vcl/opengl/program.cxx b/vcl/opengl/program.cxx
index 320b06f067a4..8b92c4bebb26 100644
--- a/vcl/opengl/program.cxx
+++ b/vcl/opengl/program.cxx
@@ -126,6 +126,12 @@ GLuint OpenGLProgram::GetUniformLocation( const OString& rName )
     return it->second;
 }
 
+void OpenGLProgram::SetUniform1f( const OString& rName, GLfloat v1 )
+{
+    GLuint nUniform = GetUniformLocation( rName );
+    glUniform1f( nUniform, v1 );
+}
+
 void OpenGLProgram::SetUniform2f( const OString& rName, GLfloat v1, GLfloat v2 )
 {
     GLuint nUniform = GetUniformLocation( rName );
@@ -170,6 +176,19 @@ void OpenGLProgram::SetColorf( const OString& rName, SalColor nColor, double fTr
         SetBlendMode( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 }
 
+void OpenGLProgram::SetColor( const OString& rName, const Color& rColor )
+{
+    GLuint nUniform = GetUniformLocation( rName );
+    glUniform4f( nUniform,
+                 ((float) rColor.GetRed()) / 255,
+                 ((float) rColor.GetGreen()) / 255,
+                 ((float) rColor.GetBlue()) / 255,
+                 1.0f - ((float) rColor.GetTransparency()) / 255 );
+
+    if( rColor.GetTransparency() > 0 )
+        SetBlendMode( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
+}
+
 void OpenGLProgram::SetColorWithIntensity( const OString& rName, const Color& rColor, long nFactor )
 {
     GLuint nUniform = GetUniformLocation( rName );
diff --git a/vcl/opengl/replaceColorFragmentShader.glsl b/vcl/opengl/replaceColorFragmentShader.glsl
new file mode 100644
index 000000000000..7c5b4c5bc7d0
--- /dev/null
+++ b/vcl/opengl/replaceColorFragmentShader.glsl
@@ -0,0 +1,25 @@
+/* -*- 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/.
+ */
+
+varying vec2 tex_coord;
+uniform sampler2D sampler;
+uniform vec4 search_color;
+uniform vec4 replace_color;
+uniform float epsilon;
+
+void main() {
+    vec4 texel = texture2D(sampler, tex_coord);
+    vec4 diff = clamp(abs(texel - search_color) - epsilon, 0.0, 1.0);
+    float bump = max(0.0, 1.0 - ceil(diff.x + diff.y + diff.z));
+    gl_FragColor = texel + bump * (replace_color - search_color);
+    gl_FragColor.r = 1.0;
+    gl_FragColor.g = 0.0;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/opengl/salbmp.cxx b/vcl/opengl/salbmp.cxx
index 078e050df1e9..94c0c870ae76 100644
--- a/vcl/opengl/salbmp.cxx
+++ b/vcl/opengl/salbmp.cxx
@@ -27,6 +27,7 @@
 #include "svdata.hxx"
 #include "salgdi.hxx"
 
+#include "opengl/program.hxx"
 #include "opengl/salbmp.hxx"
 
 static bool isValidBitCount( sal_uInt16 nBitCount )
@@ -579,9 +580,33 @@ bool OpenGLSalBitmap::Erase( const ::Color& /*rFillColor*/ )
     return false;
 }
 
-bool OpenGLSalBitmap::Replace( const Color& /*rSearchColor*/, const Color& /*rReplaceColor*/, sal_uLong /*nTol*/ )
+bool OpenGLSalBitmap::Replace( const Color& rSearchColor, const Color& rReplaceColor, sal_uLong nTol )
 {
-    return false;
+    OpenGLFramebuffer* pFramebuffer;
+    OpenGLProgram* pProgram;
+
+    GetTexture();
+    makeCurrent();
+    pProgram = mpContext->UseProgram( "textureVertexShader",
+                                      "replaceColorFragmentShader" );
+    if( !pProgram )
+        return false;
+
+    OpenGLTexture aNewTex = OpenGLTexture( mnWidth, mnHeight );
+    pFramebuffer = mpContext->AcquireFramebuffer( aNewTex );
+
+    pProgram->SetTexture( "sampler", maTexture );
+    pProgram->SetColor( "search_color", rSearchColor );
+    pProgram->SetColor( "replace_color", rReplaceColor );
+    pProgram->SetUniform1f( "epsilon", nTol / 255.0f );
+    pProgram->DrawTexture( maTexture );
+    pProgram->Clean();
+
+    mpContext->ReleaseFramebuffer( pFramebuffer );
+    maTexture = aNewTex;
+
+    CHECK_GL_ERROR();
+    return true;
 }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */