Add API to limit the acceptable scale difference when searching

for any matching cache image in QgsMapRendererCache
qgis · Jan 28, 2021 · 339516a · 339516a
1 parent ead6d06
commit 339516a
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diff --git a/python/core/auto_generated/qgsmaprenderercache.sip.in b/python/core/auto_generated/qgsmaprenderercache.sip.in
@@ -109,11 +109,16 @@ that has the same extent and scale as the cache's global extent and scale
 .. versionadded:: 3.0
 %End
 
-    bool hasAnyCacheImage( const QString &cacheKey ) const;
+    bool hasAnyCacheImage( const QString &cacheKey, double minimumScaleThreshold = 0, double maximumScaleThreshold = 0 ) const;
 %Docstring
 Returns ``True`` if the cache contains an image with the specified ``cacheKey``
 with any cache's parameters (extent and scale)
 
+The optional ``minimumScaleThreshold`` and ``maximumScaleThreshold`` arguments can be used to
+specify a range of acceptable cached scales vs current cache scale parameter. E.g. if the
+``minimumScaleThreshold`` is 0.5 and ``maximumScaleThreshold`` is 2.0, then only cached images
+with a scale between 0.5 * current cache scale and 2.0 * current cache scale will be considered.
+
 .. seealso:: :py:func:`transformedCacheImage`
 
 .. versionadded:: 3.18

diff --git a/src/core/qgsmaprenderercache.cpp b/src/core/qgsmaprenderercache.cpp
@@ -189,9 +189,25 @@ bool QgsMapRendererCache::hasCacheImage( const QString &cacheKey ) const
   }
 }
 
-bool QgsMapRendererCache::hasAnyCacheImage( const QString &cacheKey ) const
+bool QgsMapRendererCache::hasAnyCacheImage( const QString &cacheKey, double minimumScaleThreshold, double maximumScaleThreshold ) const
 {
-  return mCachedImages.contains( cacheKey );
+  auto it = mCachedImages.constFind( cacheKey );
+  if ( it != mCachedImages.constEnd() )
+  {
+    const CacheParameters &params = it.value();
+
+    // check if cached image is outside desired scale range
+    if ( minimumScaleThreshold != 0 && mMtp.mapUnitsPerPixel() < params.cachedMtp.mapUnitsPerPixel() * minimumScaleThreshold )
+      return false;
+    if ( maximumScaleThreshold != 0 && mMtp.mapUnitsPerPixel() > params.cachedMtp.mapUnitsPerPixel() * maximumScaleThreshold )
+      return false;
+
+    return true;
+  }
+  else
+  {
+    return false;
+  }
 }
 
 QImage QgsMapRendererCache::cacheImage( const QString &cacheKey ) const

diff --git a/src/core/qgsmaprenderercache.h b/src/core/qgsmaprenderercache.h
@@ -121,11 +121,16 @@ class CORE_EXPORT QgsMapRendererCache : public QObject
      * Returns TRUE if the cache contains an image with the specified \a cacheKey
      * with any cache's parameters (extent and scale)
      *
+     * The optional \a minimumScaleThreshold and \a maximumScaleThreshold arguments can be used to
+     * specify a range of acceptable cached scales vs current cache scale parameter. E.g. if the
+     * \a minimumScaleThreshold is 0.5 and \a maximumScaleThreshold is 2.0, then only cached images
+     * with a scale between 0.5 * current cache scale and 2.0 * current cache scale will be considered.
+     *
      * \see transformedCacheImage()
      *
      * \since QGIS 3.18
      */
-    bool hasAnyCacheImage( const QString &cacheKey ) const;
+    bool hasAnyCacheImage( const QString &cacheKey, double minimumScaleThreshold = 0, double maximumScaleThreshold = 0 ) const;
 
     /**
      * Returns the cached image for the specified \a cacheKey. The \a cacheKey usually

diff --git a/tests/src/core/testqgsmaprenderercache.cpp b/tests/src/core/testqgsmaprenderercache.cpp
@@ -20,12 +20,12 @@
 #include "qgsmaptopixel.h"
 #include "qgsrectangle.h"
 
-class TestQgsMapRendereCache: public QObject
+class TestQgsMapRendererCache: public QObject
 {
     Q_OBJECT
 
   public:
-    TestQgsMapRendereCache();
+    TestQgsMapRendererCache();
 
   private slots:
     void initTestCase();// will be called before the first testfunction is executed.
@@ -37,28 +37,28 @@ class TestQgsMapRendereCache: public QObject
 };
 
 
-TestQgsMapRendereCache::TestQgsMapRendereCache() = default;
+TestQgsMapRendererCache::TestQgsMapRendererCache() = default;
 
-void TestQgsMapRendereCache::initTestCase()
+void TestQgsMapRendererCache::initTestCase()
 {
   QgsApplication::init();
   QgsApplication::initQgis();
 }
 
-void TestQgsMapRendereCache::cleanupTestCase()
+void TestQgsMapRendererCache::cleanupTestCase()
 {
   QgsApplication::exitQgis();
 }
 
-void TestQgsMapRendereCache::init()
+void TestQgsMapRendererCache::init()
 {
 }
 
-void TestQgsMapRendereCache::cleanup()
+void TestQgsMapRendererCache::cleanup()
 {
 }
 
-void TestQgsMapRendereCache::testCache()
+void TestQgsMapRendererCache::testCache()
 {
   QgsMapRendererCache cache;
   QImage imgRed( 100, 100, QImage::Format::Format_ARGB32_Premultiplied );
@@ -80,12 +80,14 @@ void TestQgsMapRendereCache::testCache()
   QVERIFY( !cache.hasCacheImage( imgRedKey ) );
   QVERIFY( cache.hasCacheImage( imgBlueKey ) );
   QVERIFY( cache.hasAnyCacheImage( imgBlueKey ) );
+  QVERIFY( cache.hasAnyCacheImage( imgBlueKey, 0.9, 1.1 ) );
 
   cache.setCacheImage( imgRedKey, imgRed );
   QVERIFY( cache.hasCacheImage( imgRedKey ) );
   QVERIFY( cache.hasCacheImage( imgBlueKey ) );
   QVERIFY( cache.hasAnyCacheImage( imgBlueKey ) );
   QVERIFY( cache.hasAnyCacheImage( imgRedKey ) );
+  QVERIFY( cache.hasAnyCacheImage( imgRedKey, 0.9, 1.1 ) );
 
   {
     QImage img = cache.cacheImage( imgBlueKey );
@@ -104,12 +106,39 @@ void TestQgsMapRendereCache::testCache()
   QVERIFY( !cache.hasCacheImage( imgRedKey ) );
   QVERIFY( !cache.hasCacheImage( imgBlueKey ) );
   QVERIFY( cache.hasAnyCacheImage( imgBlueKey ) );
-  QVERIFY( cache.hasAnyCacheImage( imgRedKey ) );
+  QVERIFY( cache.hasAnyCacheImage( imgBlueKey, 0.9, 1.1 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgRedKey, 0.9, 1.1 ) );
 
   QImage transformed = cache.transformedCacheImage( imgBlueKey, mtp2 );
   QVERIFY( transformed.pixelColor( 30, 20 ) == Qt::transparent );
   QVERIFY( transformed.pixelColor( 10, 20 ) == Qt::blue );
 
+  QgsMapToPixel mtp3( 2, 70, 50, 100, 100, 0.0 ); // scale by 2
+  cache.updateParameters( extent2, mtp3 );
+  QVERIFY( !cache.hasCacheImage( imgRedKey ) );
+  QVERIFY( !cache.hasCacheImage( imgBlueKey ) );
+  QVERIFY( cache.hasAnyCacheImage( imgBlueKey ) );
+  // outside of range
+  QVERIFY( !cache.hasAnyCacheImage( imgBlueKey, 0.9, 1.1 ) );
+  QVERIFY( !cache.hasAnyCacheImage( imgRedKey, 0.9, 1.1 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgBlueKey, 0.9, 0 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgRedKey, 0.9, 0 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgBlueKey, 0.9, 2.0 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgRedKey, 0.9, 2.0 ) );
+
+  QgsMapToPixel mtp4( 0.5, 70, 50, 100, 100, 0.0 ); // scale by 0.5
+  cache.updateParameters( extent2, mtp4 );
+  QVERIFY( !cache.hasCacheImage( imgRedKey ) );
+  QVERIFY( !cache.hasCacheImage( imgBlueKey ) );
+  QVERIFY( cache.hasAnyCacheImage( imgBlueKey ) );
+  // outside of range
+  QVERIFY( !cache.hasAnyCacheImage( imgBlueKey, 0.9, 1.1 ) );
+  QVERIFY( !cache.hasAnyCacheImage( imgRedKey, 0.9, 1.1 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgBlueKey, 0, 1.1 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgRedKey, 0, 1.1 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgBlueKey, 0.5, 1.1 ) );
+  QVERIFY( cache.hasAnyCacheImage( imgRedKey, 0.5, 1.1 ) );
+
   /* we can replace the cache image */
   cache.setCacheImage( imgBlueKey, transformed );
   QVERIFY( cache.hasCacheImage( imgBlueKey ) );
@@ -126,5 +155,5 @@ void TestQgsMapRendereCache::testCache()
 }
 
 
-QGSTEST_MAIN( TestQgsMapRendereCache )
+QGSTEST_MAIN( TestQgsMapRendererCache )
 #include "testqgsmaprenderercache.moc"