WIP: live preview

Instead of simulating what e.g. move contents does, bypass the undo
framework and modify the image contents directly. When the dialog
is accepted or rejected, either commit or rollback the changes.
This allows live preview of certain changes to image contents.

Fixes #171

app/qml/ui/MoveContentsDialog.qml

@@ -32,24 +32,25 @@ Dialog {
     focus: true
     enabled: isLayeredImageProject
 
-    property Project project
+    property LayeredImageProject project
     property bool isLayeredImageProject: project && project.type === Project.LayeredImageType
 
+    function updateLivePreview() {
+        project.moveContents(xDistanceSpinBox.value, yDistanceSpinBox.value, onlyMoveVisibleLayersCheckBox.checked)
+    }
+
     onAboutToShow: {
         if (project) {
             xDistanceSpinBox.value = 0
             yDistanceSpinBox.value = 0
             xDistanceSpinBox.contentItem.forceActiveFocus()
-            imagePreview.source = "image://project"
-        }
-    }
 
-    onAboutToHide: {
-        // Ensure that an up-to-date image is assign when we open by clearing it when we close.
-        imagePreview.source = ""
+            project.beginLivePreview()
+        }
     }
 
-    onAccepted: project.moveContents(xDistanceSpinBox.value, yDistanceSpinBox.value, onlyMoveVisibleLayersCheckBox.checked)
+    onAccepted: project.endLivePreview(LayeredImageProject.CommitModificaton)
+    onRejected: project.endLivePreview(LayeredImageProject.RollbackModification)
 
     contentItem: ColumnLayout {
         GridLayout {
@@ -75,6 +76,8 @@ Dialog {
                 ToolTip.delay: UiConstants.toolTipDelay
                 ToolTip.timeout: UiConstants.toolTipTimeout
 
+                onValueModified: root.updateLivePreview()
+
                 Keys.onReturnPressed: root.accept()
             }
 
@@ -98,6 +101,8 @@ Dialog {
                 ToolTip.delay: UiConstants.toolTipDelay
                 ToolTip.timeout: UiConstants.toolTipTimeout
 
+                onValueModified: root.updateLivePreview()
+
                 Keys.onReturnPressed: root.accept()
             }
 
@@ -116,55 +121,9 @@ Dialog {
                 ToolTip.delay: UiConstants.toolTipDelay
                 ToolTip.timeout: UiConstants.toolTipTimeout
 
-                Keys.onReturnPressed: root.accept()
-            }
-
-            Rectangle {
-                id: imagePreviewBackground
-                objectName: "imagePreviewBackground"
-                color: "black"
-                clip: true
+                onToggled: root.updateLivePreview()
 
-                Layout.columnSpan: 2
-                Layout.preferredWidth: 400
-                Layout.preferredHeight: 400
-                Layout.fillWidth: true
-                Layout.fillHeight: true
-
-                Image {
-                    objectName: "imagePreviewOldBounds"
-                    // QQuickImage uses ceil.
-                    x: Math.ceil((parent.width - imagePreview.paintedWidth) / 2)
-                    y: Math.ceil((parent.height - imagePreview.paintedHeight) / 2)
-                    width: imagePreview.paintedWidth
-                    height: imagePreview.paintedHeight
-                    source: "qrc:/images/checker.png"
-                    fillMode: Image.Tile
-                    smooth: false
-                    clip: true
-
-                    // We want the project's image to be clipped by its old bounds,
-                    // as that's what it will actually look like after moving.
-                    // That's why it's a child of the old bounds image.
-                    Image {
-                        id: imagePreview
-                        // Our parent has to be positioned correctly based on our painted size,
-                        // which means we must deduct their position to get ours.
-                        x: Math.ceil((xDistanceSpinBox.value * widthScale) - parent.x)
-                        y: Math.ceil((yDistanceSpinBox.value * heightScale) - parent.y)
-                        width: imagePreviewBackground.width
-                        height: imagePreviewBackground.height
-                        fillMode: Image.PreserveAspectFit
-                        smooth: false
-                        // Ensure that we get up-to-date images from the provider.
-                        cache: false
-
-                        // The image is scaled to fit the viewport (imagePreviewBackground),
-                        // so our x and y position must be scaled to account for that.
-                        readonly property int widthScale: paintedWidth / implicitWidth
-                        readonly property int heightScale: paintedHeight / implicitHeight
-                    }
-                }
+                Keys.onReturnPressed: root.accept()
             }
         }
     }

lib/imagecanvas.cpp

@@ -981,6 +981,7 @@ void ImageCanvas::connectSignals()
     connect(mProject, SIGNAL(preProjectSaved()), this, SLOT(saveState()));
     connect(mProject, SIGNAL(aboutToBeginMacro(QString)),
         this, SLOT(onAboutToBeginMacro(QString)));
+    connect(mProject, SIGNAL(livePreviewChanged()), this, SLOT(requestContentPaint()));
 
     connect(window(), SIGNAL(activeFocusItemChanged()), this, SLOT(updateWindowCursorShape()));
 }
@@ -997,6 +998,7 @@ void ImageCanvas::disconnectSignals()
     mProject->disconnect(SIGNAL(preProjectSaved()), this, SLOT(saveState()));
     mProject->disconnect(SIGNAL(aboutToBeginMacro(QString)),
         this, SLOT(onAboutToBeginMacro(QString)));
+    mProject->disconnect(SIGNAL(livePreviewChanged()), this, SLOT(requestContentPaint()));
 
     if (window()) {
         window()->disconnect(SIGNAL(activeFocusItemChanged()), this, SLOT(updateWindowCursorShape()));

lib/imageproject.h

@@ -87,6 +87,7 @@ public slots:
 
     QUrl mImageUrl;
     QImage mImage;
+
     bool mUsingAnimation = false;
     bool mHasUsedAnimation = false;
     AnimationSystem mAnimationSystem;