Fixes a wrong dpi resolution in images exported from composer

agiudiceandrea · nyalldawson · commit 4f05da4a0de9 · 2018-04-13T10:58:47.000+10:00
In order to avoid wrong dpi resolution in images exported from composer we need to round the dpi resolution calculated "using average of derived x/y dpi" instead of truncate it to int.
diff --git a/src/core/composer/qgscomposition.cpp b/src/core/composer/qgscomposition.cpp
@@ -3058,8 +3058,8 @@ QImage QgsComposition::printPageAsRaster( int page, QSize imageSize, int dpi )
   {
     //output size in pixels specified, calculate resolution using average of
     //derived x/y dpi
-    resolution = ( imageSize.width() / mPageWidth
-                   + imageSize.height() / mPageHeight ) / 2.0 * 25.4;
+    resolution = qRound(( imageSize.width() / mPageWidth
+                          + imageSize.height() / mPageHeight ) / 2.0 * 25.4 );
   }
   else if ( dpi > 0 )
   {
@@ -3092,8 +3092,8 @@ QImage QgsComposition::renderRectAsRaster( const QRectF& rect, QSize imageSize,
   {
     //output size in pixels specified, calculate resolution using average of
     //derived x/y dpi
-    resolution = ( imageSize.width() / rect.width()
-                   + imageSize.height() / rect.height() ) / 2.0 * 25.4;
+    resolution = qRound(( imageSize.width() / rect.width()
+                          + imageSize.height() / rect.height() ) / 2.0 * 25.4 );
   }
   else if ( dpi > 0 )
   {

Original file line number	Diff line number	Diff line change
`@@ -3058,8 +3058,8 @@ QImage QgsComposition::printPageAsRaster( int page, QSize imageSize, int dpi )`
`3058`	`3058`	`{`
`3059`	`3059`	`//output size in pixels specified, calculate resolution using average of`
`3060`	`3060`	`//derived x/y dpi`
`3061`		`- resolution = ( imageSize.width() / mPageWidth`
`3062`		`- + imageSize.height() / mPageHeight ) / 2.0 * 25.4;`
	`3061`	`+ resolution = qRound(( imageSize.width() / mPageWidth`
	`3062`	`+ + imageSize.height() / mPageHeight ) / 2.0 * 25.4 );`
`3063`	`3063`	`}`
`3064`	`3064`	`else if ( dpi > 0 )`
`3065`	`3065`	`{`
`@@ -3092,8 +3092,8 @@ QImage QgsComposition::renderRectAsRaster( const QRectF& rect, QSize imageSize,`
`3092`	`3092`	`{`
`3093`	`3093`	`//output size in pixels specified, calculate resolution using average of`
`3094`	`3094`	`//derived x/y dpi`
`3095`		`- resolution = ( imageSize.width() / rect.width()`
`3096`		`- + imageSize.height() / rect.height() ) / 2.0 * 25.4;`
	`3095`	`+ resolution = qRound(( imageSize.width() / rect.width()`
	`3096`	`+ + imageSize.height() / rect.height() ) / 2.0 * 25.4 );`
`3097`	`3097`	`}`
`3098`	`3098`	`else if ( dpi > 0 )`
`3099`	`3099`	`{`