EffectComposer: Fix effect preview zoom

Zoom must scale the component showing the preview, not the source
image. This way the effect stays consistent regardless of the zoom
level.

Fixes: QDS-11899
Change-Id: I550eb9ff693c24a853f5c25d9d79fa146448663f
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

2 files changed, 128 insertions, 109 deletions

diff --git a/share/qtcreator/qmldesigner/effectComposerQmlSources/EffectComposerPreview.qml b/share/qtcreator/qmldesigner/effectComposerQmlSources/EffectComposerPreview.qml
index 50c8e32c71..c832b2f370 100644
--- a/share/qtcreator/qmldesigner/effectComposerQmlSources/EffectComposerPreview.qml
+++ b/share/qtcreator/qmldesigner/effectComposerQmlSources/EffectComposerPreview.qml
@@ -22,11 +22,13 @@ Column {
 
     readonly property int previewMargin: 5
 
+    property real previewScale: 1
+
     // Create a dummy parent to host the effect qml object
     function createNewComponent() {
         // If we have a working effect, do not show preview image as it shows through
         // transparent parts of the final image
-        source.visible = false;
+        placeHolder.visible = false;
 
         var oldComponent = componentParent.children[0];
         if (oldComponent)
@@ -48,7 +50,7 @@ Column {
                 errorLine = e.lineNumber;
             }
             effectComposerModel.setEffectError(errorString, 0, errorLine);
-            source.visible = true;
+            placeHolder.visible = true;
         }
     }
 
@@ -84,42 +86,42 @@ Column {
             anchors.verticalCenter: parent.verticalCenter
 
             HelperWidgets.AbstractButton {
-                enabled: sourceImage.scale < 3
+                enabled: root.previewScale < 3
                 style: StudioTheme.Values.viewBarButtonStyle
                 buttonIcon: StudioTheme.Constants.zoomIn_medium
                 tooltip: qsTr("Zoom In")
 
                 onClicked: {
-                    sourceImage.enableAnim(true)
-                    sourceImage.scale += .2
-                    sourceImage.enableAnim(false)
+                    imageScaler.enableAnim(true)
+                    root.previewScale += .2
+                    imageScaler.enableAnim(false)
                     zoomIndicator.show()
                 }
             }
 
             HelperWidgets.AbstractButton {
-                enabled: sourceImage.scale > .4
+                enabled: root.previewScale > .4
                 style: StudioTheme.Values.viewBarButtonStyle
                 buttonIcon: StudioTheme.Constants.zoomOut_medium
                 tooltip: qsTr("Zoom out")
 
                 onClicked: {
-                    sourceImage.enableAnim(true)
-                    sourceImage.scale -= .2
-                    sourceImage.enableAnim(false)
+                    imageScaler.enableAnim(true)
+                    root.previewScale -= .2
+                    imageScaler.enableAnim(false)
                     zoomIndicator.show()
                 }
             }
 
             HelperWidgets.AbstractButton {
-                enabled: sourceImage.scale !== 1 || sourceImage.x !== root.previewMargin
-                                                 || sourceImage.y !== root.previewMargin
+                enabled: root.previewScale !== 1 || imageScaler.x !== root.previewMargin
+                                                 || imageScaler.y !== root.previewMargin
                 style: StudioTheme.Values.viewBarButtonStyle
                 buttonIcon: StudioTheme.Constants.fitAll_medium
                 tooltip: qsTr("Reset View")
 
                 onClicked: {
-                    sourceImage.resetTransforms()
+                    imageScaler.resetTransforms()
                 }
             }
         }
@@ -187,8 +189,8 @@ Column {
             property bool panning: false
 
             onPressed:  {
-                pressX = mouseX - sourceImage.x
-                pressY = mouseY - sourceImage.y
+                pressX = mouseX - imageScaler.x
+                pressY = mouseY - imageScaler.y
                 panning = true
             }
 
@@ -197,22 +199,21 @@ Column {
             }
 
             onWheel: (wheel) => {
-                let prevScale = sourceImage.scale
+                let oldPoint = imageScaler.mapFromItem(mouseArea, Qt.point(wheel.x, wheel.y))
 
                 if (wheel.angleDelta.y > 0) {
-                    if (sourceImage.scale < 3)
-                        sourceImage.scale += .2
+                    if (root.previewScale < 3)
+                        root.previewScale += .2
                 } else {
-                    if (sourceImage.scale > .4)
-                        sourceImage.scale -= .2
+                    if (root.previewScale > .4)
+                        root.previewScale -= .2
                 }
 
-                let dScale = sourceImage.scale - prevScale
-
-                sourceImage.x += (sourceImage.x + sourceImage.width * .5 - wheel.x) * dScale;
-                sourceImage.y += (sourceImage.y + sourceImage.height * .5 - wheel.y) * dScale;
+                let newPoint = imageScaler.mapFromItem(mouseArea, Qt.point(wheel.x, wheel.y))
+                imageScaler.x -= (oldPoint.x - newPoint.x) * imageScaler.scale
+                imageScaler.y -= (oldPoint.y - newPoint.y) * imageScaler.scale
 
-                sourceImage.checkBounds()
+                imageScaler.checkBounds()
                 zoomIndicator.show()
             }
 
@@ -222,117 +223,135 @@ Column {
                 repeat: true
 
                 onTriggered: {
-                    sourceImage.x = mouseArea.mouseX - mouseArea.pressX
-                    sourceImage.y = mouseArea.mouseY - mouseArea.pressY
-                    sourceImage.checkBounds()
+                    imageScaler.x = mouseArea.mouseX - mouseArea.pressX
+                    imageScaler.y = mouseArea.mouseY - mouseArea.pressY
+                    imageScaler.checkBounds()
                 }
             }
         }
 
+        Image {
+            id: placeHolder
+            anchors.fill: parent
+            anchors.margins: root.previewMargin
+            fillMode: Image.PreserveAspectFit
+            source: imagesComboBox.selectedImage
+            smooth: true
+        }
+
         Item { // Source item as a canvas (render target) for effect
             id: source
-            anchors.fill: parent
+            width: sourceImage.sourceSize.width
+            height: sourceImage.sourceSize.height
             layer.enabled: true
             layer.mipmap: true
             layer.smooth: true
+            visible: false
 
             Image {
                 id: sourceImage
 
-                function checkBounds() {
-                    let edgeMargin = 10
-                    // correction factor to account for an observation that edgeMargin decreases
-                    // with increased zoom
-                    let corrFactor = 10 * sourceImage.scale
-                    let imgW2 = sourceImage.paintedWidth * sourceImage.scale * .5
-                    let imgH2 = sourceImage.paintedHeight * sourceImage.scale * .5
-                    let srcW2 = source.width * .5
-                    let srcH2 = source.height * .5
-
-                    if (sourceImage.x < -srcW2 - imgW2 + edgeMargin + corrFactor)
-                        sourceImage.x = -srcW2 - imgW2 + edgeMargin + corrFactor
-                    else if (x > srcW2 + imgW2 - edgeMargin - corrFactor)
-                        sourceImage.x = srcW2 + imgW2 - edgeMargin - corrFactor
-
-                    if (sourceImage.y < -srcH2 - imgH2 + edgeMargin + corrFactor)
-                        sourceImage.y = -srcH2 - imgH2 + edgeMargin + corrFactor
-                    else if (y > srcH2 + imgH2 - edgeMargin - corrFactor)
-                        sourceImage.y = srcH2 + imgH2 - edgeMargin - corrFactor
-                }
+                onSourceChanged: imageScaler.resetTransforms()
 
-                function resetTransforms() {
-                    sourceImage.enableAnim(true)
-                    sourceImage.scale = 1
-                    sourceImage.x = root.previewMargin
-                    sourceImage.y = root.previewMargin
-                    sourceImage.enableAnim(false)
-                }
-
-                function enableAnim(flag) {
-                    xBehavior.enabled = flag
-                    yBehavior.enabled = flag
-                    scaleBehavior.enabled = flag
-                }
+                fillMode: Image.Pad
 
-                onSourceChanged: sourceImage.resetTransforms()
-
-                fillMode: Image.PreserveAspectFit
-
-                x: root.previewMargin
-                y: root.previewMargin
-                width: parent.width - root.previewMargin * 2
-                height: parent.height - root.previewMargin * 2
                 source: imagesComboBox.selectedImage
                 smooth: true
+            }
+        }
 
-                Behavior on x {
-                    id: xBehavior
+        BlurHelper {
+            id: blurHelper
+            source: source
+            property int blurMax: g_propertyData.blur_helper_max_level ? g_propertyData.blur_helper_max_level : 64
+            property real blurMultiplier: g_propertyData.blurMultiplier ? g_propertyData.blurMultiplier : 0
+        }
 
-                    enabled: false
-                    NumberAnimation {
-                        duration: 200
-                        easing.type: Easing.OutQuad
-                    }
+        Item {
+            id: imageScaler
+            x: root.previewMargin
+            y: root.previewMargin
+            width: parent.width - root.previewMargin * 2
+            height: parent.height - root.previewMargin * 2
+
+            scale: root.previewScale * (width > height ? height / sourceImage.sourceSize.height
+                                                       : width / sourceImage.sourceSize.width)
+
+            Behavior on x {
+                id: xBehavior
+
+                enabled: false
+                NumberAnimation {
+                    duration: 200
+                    easing.type: Easing.OutQuad
                 }
+            }
 
-                Behavior on y {
-                    id: yBehavior
+            Behavior on y {
+                id: yBehavior
 
-                    enabled: false
-                    NumberAnimation {
-                        duration: 200
-                        easing.type: Easing.OutQuad
-                    }
+                enabled: false
+                NumberAnimation {
+                    duration: 200
+                    easing.type: Easing.OutQuad
                 }
+            }
 
-                Behavior on scale {
-                    id: scaleBehavior
+            Behavior on scale {
+                id: scaleBehavior
 
-                    enabled: false
-                    NumberAnimation {
-                        duration: 200
-                        easing.type: Easing.OutQuad
-                    }
+                enabled: false
+                NumberAnimation {
+                    duration: 200
+                    easing.type: Easing.OutQuad
                 }
             }
-        }
 
-        BlurHelper {
-            id: blurHelper
-            source: source
-            property int blurMax: g_propertyData.blur_helper_max_level ? g_propertyData.blur_helper_max_level : 64
-            property real blurMultiplier: g_propertyData.blurMultiplier ? g_propertyData.blurMultiplier : 0
-        }
+            function checkBounds() {
+                let edgeMargin = 10
+                // correction factor to account for an observation that edgeMargin decreases
+                // with increased zoom
+                let corrFactor = 10 * imageScaler.scale
+                let imgW2 = sourceImage.paintedWidth * imageScaler.scale * .5
+                let imgH2 = sourceImage.paintedHeight * imageScaler.scale * .5
+                let srcW2 = width * .5
+                let srcH2 = height * .5
+
+                if (imageScaler.x < -srcW2 - imgW2 + edgeMargin + corrFactor)
+                    imageScaler.x = -srcW2 - imgW2 + edgeMargin + corrFactor
+                else if (x > srcW2 + imgW2 - edgeMargin - corrFactor)
+                    imageScaler.x = srcW2 + imgW2 - edgeMargin - corrFactor
+
+                if (imageScaler.y < -srcH2 - imgH2 + edgeMargin + corrFactor)
+                    imageScaler.y = -srcH2 - imgH2 + edgeMargin + corrFactor
+                else if (y > srcH2 + imgH2 - edgeMargin - corrFactor)
+                    imageScaler.y = srcH2 + imgH2 - edgeMargin - corrFactor
+            }
 
-        Item {
-            id: componentParent
-            width: source.width
-            height: source.height
-            anchors.centerIn: parent
-            // Cache the layer. This way heavy shaders rendering doesn't
-            // slow down code editing & rest of the UI.
-            layer.enabled: true
-            layer.smooth: true
+            function resetTransforms() {
+                imageScaler.enableAnim(true)
+                root.previewScale = 1
+                imageScaler.x = root.previewMargin
+                imageScaler.y = root.previewMargin
+                imageScaler.enableAnim(false)
+            }
+
+            function enableAnim(flag) {
+                xBehavior.enabled = flag
+                yBehavior.enabled = flag
+                scaleBehavior.enabled = flag
+            }
+
+            Item {
+                id: componentParent
+                width: source.width
+                height: source.height
+                anchors.centerIn: parent
+                // Cache the layer. This way heavy shaders rendering doesn't
+                // slow down code editing & rest of the UI.
+                layer.enabled: true
+                layer.smooth: true
+            }
         }
 
         Rectangle {
@@ -349,7 +368,7 @@ Column {
             }
 
             Text {
-                text: Math.round(sourceImage.scale * 100) + "%"
+                text: Math.round(root.previewScale * 100) + "%"
                 color: StudioTheme.Values.themeTextColor
                 anchors.centerIn: parent
             }
diff --git a/src/plugins/effectcomposer/effectcomposermodel.h b/src/plugins/effectcomposer/effectcomposermodel.h
index c0eb76f0b9..871d0c7298 100644
--- a/src/plugins/effectcomposer/effectcomposermodel.h
+++ b/src/plugins/effectcomposer/effectcomposermodel.h
@@ -178,7 +178,7 @@ private:
     QList<CompositionNode *> m_nodes;
 
     int m_selectedIndex = -1;
-    bool m_isEmpty = true;
+    bool m_isEmpty = false;  // Init to false to force initial bake after setup
     bool m_hasUnsavedChanges = false;
     // True when shaders haven't changed since last baking
     bool m_shadersUpToDate = true;