[tests] Add method for setting size tolerance to render checker,

add some size tolerance to legend renderer test

python/core/qgsrenderchecker.sip

@@ -62,6 +62,14 @@ class QgsRenderChecker
      * @note added in 2.1
      */
     void setColorTolerance( unsigned int theColorTolerance );
+
+    /** Sets the largest allowable difference in size between the rendered and the expected image.
+     * @param xTolerance x tolerance in pixels
+     * @param yTolerance y tolerance in pixels
+     * @note added in QGIS 2.12
+     */
+    void setSizeTolerance( int xTolerance, int yTolerance );
+
     /**
      * Test using renderer to generate the image to be compared.
      * @param theTestName - to be used as the basis for writing a file to

src/core/qgsrenderchecker.cpp

@@ -37,6 +37,8 @@ QgsRenderChecker::QgsRenderChecker()
     , mExpectedImageFile( "" )
     , mMismatchCount( 0 )
     , mColorTolerance( 0 )
+    , mMaxSizeDifferenceX( 0 )
+    , mMaxSizeDifferenceY( 0 )
     , mElapsedTimeTarget( 0 )
     , mBufferDashMessages( false )
 {
@@ -374,13 +376,24 @@ bool QgsRenderChecker::compareImages( QString theTestName,
 
   if ( mMatchTarget != myPixelCount )
   {
-    qDebug( "Test image and result image for %s are different dimensions - FAILING!", theTestName.toLocal8Bit().constData() );
-    mReport += "<tr><td colspan=3>";
-    mReport += "<font color=red>Expected image and result image for " + theTestName + " are different dimensions - FAILING!</font>";
-    mReport += "</td></tr>";
-    mReport += myImagesString;
-    delete maskImage;
-    return false;
+    qDebug( "Test image and result image for %s are different dimensions", theTestName.toLocal8Bit().constData() );
+
+    if ( qAbs( myExpectedImage.width() - myResultImage.width() ) > mMaxSizeDifferenceX ||
+         qAbs( myExpectedImage.height() - myResultImage.height() ) > mMaxSizeDifferenceY )
+    {
+      mReport += "<tr><td colspan=3>";
+      mReport += "<font color=red>Expected image and result image for " + theTestName + " are different dimensions - FAILING!</font>";
+      mReport += "</td></tr>";
+      mReport += myImagesString;
+      delete maskImage;
+      return false;
+    }
+    else
+    {
+      mReport += "<tr><td colspan=3>";
+      mReport += "Expected image and result image for " + theTestName + " are different dimensions, but within tolerance";
+      mReport += "</td></tr>";
+    }
   }
 
   //
@@ -388,16 +401,19 @@ bool QgsRenderChecker::compareImages( QString theTestName,
   // dissimilar pixel values there are
   //
 
+  int maxHeight = qMin( myExpectedImage.height(), myResultImage.height() );
+  int maxWidth = qMin( myExpectedImage.width(), myResultImage.width() );
+
   mMismatchCount = 0;
   int colorTolerance = ( int ) mColorTolerance;
-  for ( int y = 0; y < myExpectedImage.height(); ++y )
+  for ( int y = 0; y < maxHeight; ++y )
   {
     const QRgb* expectedScanline = ( const QRgb* )myExpectedImage.constScanLine( y );
     const QRgb* resultScanline = ( const QRgb* )myResultImage.constScanLine( y );
     const QRgb* maskScanline = hasMask ? ( const QRgb* )maskImage->constScanLine( y ) : 0;
     QRgb* diffScanline = ( QRgb* )myDifferenceImage.scanLine( y );
 
-    for ( int x = 0; x < myExpectedImage.width(); ++x )
+    for ( int x = 0; x < maxWidth; ++x )
     {
       int maskTolerance = hasMask ? qRed( maskScanline[ x ] ) : 0;
       int pixelTolerance = qMax( colorTolerance, maskTolerance );

src/core/qgsrenderchecker.h

@@ -41,11 +41,12 @@ class CORE_EXPORT QgsRenderChecker
     QgsRenderChecker();
 
     //! Destructor
-    ~QgsRenderChecker() {};
+    ~QgsRenderChecker() {}
 
     QString controlImagePath() const;
 
-    QString report() { return mReport; };
+    QString report() { return mReport; }
+
     float matchPercent()
     {
       return static_cast<float>( mMismatchCount ) /
@@ -55,7 +56,7 @@ class CORE_EXPORT QgsRenderChecker
     unsigned int matchTarget() { return mMatchTarget; }
     //only records time for actual render part
     int elapsedTime() { return mElapsedTime; }
-    void setElapsedTimeTarget( int theTarget ) { mElapsedTimeTarget = theTarget; };
+    void setElapsedTimeTarget( int theTarget ) { mElapsedTimeTarget = theTarget; }
 
     /** Base directory name for the control image (with control image path
       * suffixed) the path to the image will be constructed like this:
@@ -96,6 +97,14 @@ class CORE_EXPORT QgsRenderChecker
      * @note added in 2.1
      */
     void setColorTolerance( unsigned int theColorTolerance ) { mColorTolerance = theColorTolerance; }
+
+    /** Sets the largest allowable difference in size between the rendered and the expected image.
+     * @param xTolerance x tolerance in pixels
+     * @param yTolerance y tolerance in pixels
+     * @note added in QGIS 2.12
+     */
+    void setSizeTolerance( int xTolerance, int yTolerance ) { mMaxSizeDifferenceX = xTolerance; mMaxSizeDifferenceY = yTolerance; }
+
     /**
      * Test using renderer to generate the image to be compared.
      * @param theTestName - to be used as the basis for writing a file to
@@ -173,6 +182,8 @@ class CORE_EXPORT QgsRenderChecker
     QString mControlName;
     unsigned int mMismatchCount;
     unsigned int mColorTolerance;
+    int mMaxSizeDifferenceX;
+    int mMaxSizeDifferenceY;
     int mElapsedTimeTarget;
     QgsMapSettings mMapSettings;
     QString mControlPathPrefix;

tests/src/core/testqgslegendrenderer.cpp

@@ -67,6 +67,7 @@ static bool _verifyImage( const QString& testName, QString &report )
   QgsRenderChecker checker;
   checker.setControlName( "expected_" + testName );
   checker.setRenderedImage( _fileNameForTest( testName ) );
+  checker.setSizeTolerance( 3, 3 );
   bool equal = checker.compareImages( testName, 500 );
   report += checker.report();
   return equal;