2 * Copyright (c) 2017 Samsung Electronics Co., Ltd.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
21 #include "gaussian-blur.h"
22 #include "pixel-buffer-impl.h"
35 void ConvoluteAndTranspose( unsigned char* inBuffer,
36 unsigned char* outBuffer,
37 const unsigned int bufferWidth,
38 const unsigned int bufferHeight,
39 const float blurRadius )
41 // Calculate the weights for gaussian blur
42 int radius = static_cast<int>( std::ceil( blurRadius ) );
43 int rows = radius * 2 + 1;
45 float sigma = ( blurRadius < Math::MACHINE_EPSILON_1 ) ? 0.0f : blurRadius * 0.4f + 0.6f; // The same equation used by Android
46 float sigma22 = 2.0f * sigma * sigma;
47 float sqrtSigmaPi2 = std::sqrt( 2.0f * Math::PI ) * sigma;
48 float radius2 = radius * radius;
49 float normalizeFactor = 0.0f;
51 float* weightMatrix = new float[rows];
54 for ( int row = -radius; row <= radius; row++ )
56 float distance = row * row;
57 if ( distance > radius2 )
59 weightMatrix[index] = 0.0f;
63 weightMatrix[index] = static_cast<float>( std::exp( -( distance ) / sigma22 ) / sqrtSigmaPi2 );
65 normalizeFactor += weightMatrix[index];
69 for ( int i = 0; i < rows; i++ )
71 weightMatrix[i] /= normalizeFactor;
74 // Perform the convolution and transposition using the weights
76 int columns2 = columns / 2;
77 for ( unsigned int y = 0; y < bufferHeight; y++ )
79 unsigned int targetPixelIndex = y;
80 unsigned int ioffset = y * bufferWidth;
81 for ( unsigned int x = 0; x < bufferWidth; x++ )
83 float r = 0.0f, g = 0.0f, b = 0.0f, a = 0.0f;
84 int weightColumnOffset = columns2;
85 for ( int column = -columns2; column <= columns2; column++ )
87 float weight = weightMatrix[weightColumnOffset + column];
88 if ( fabsf( weight ) > Math::MACHINE_EPSILON_1 )
91 ix = std::max( 0, std::min( ix, static_cast<int>( bufferWidth - 1 ) ) );
92 unsigned int sourcePixelIndex = ioffset + ix;
93 r += weight * inBuffer[sourcePixelIndex*4];
94 g += weight * inBuffer[sourcePixelIndex*4+1];
95 b += weight * inBuffer[sourcePixelIndex*4+2];
96 a += weight * inBuffer[sourcePixelIndex*4+3];
100 outBuffer[targetPixelIndex*4] = std::max( 0, std::min( static_cast<int>( r + 0.5f ), 255 ) );
101 outBuffer[targetPixelIndex*4+1] = std::max( 0, std::min( static_cast<int>( g + 0.5f ), 255 ) );
102 outBuffer[targetPixelIndex*4+2] = std::max( 0, std::min( static_cast<int>( b + 0.5f ), 255 ) );
103 outBuffer[targetPixelIndex*4+3] = std::max( 0, std::min( static_cast<int>( a + 0.5f ), 255 ) );
105 targetPixelIndex += bufferHeight;
109 delete [] weightMatrix;
112 void PerformGaussianBlurRGBA( PixelBuffer& buffer, const float blurRadius )
114 unsigned int bufferWidth = buffer.GetWidth();
115 unsigned int bufferHeight = buffer.GetHeight();
117 // Create a temporary buffer for the two-pass blur
118 PixelBufferPtr softShadowImageBuffer = PixelBuffer::New( bufferWidth, bufferHeight, Pixel::RGBA8888 );
119 memcpy( softShadowImageBuffer->GetBuffer(), buffer.GetBuffer(), 4u * bufferWidth * bufferHeight );
121 // We perform the blur first but write its output image buffer transposed, so that we
122 // can just do it in two passes. The first pass blurs horizontally and transposes, the
123 // second pass does the same, but as the image is now transposed, it's really doing a
124 // vertical blur. The second transposition makes the image the right way up again. This
125 // is much faster than doing a 2D convolution.
126 ConvoluteAndTranspose( buffer.GetBuffer(), softShadowImageBuffer->GetBuffer(), bufferWidth, bufferHeight, blurRadius );
127 ConvoluteAndTranspose( softShadowImageBuffer->GetBuffer(), buffer.GetBuffer(), bufferHeight, bufferWidth, blurRadius );
129 // On leaving scope, softShadowImageBuffer will get destroyed.
132 } //namespace Adaptor
134 }// namespace Internal