[nostalgia/core/studio] Add support for dragging cursor around tile sheet editor

src/nostalgia/core/studio/Pixel.qml

@@ -27,9 +27,4 @@ Rectangle {
 		anchors.bottom: pixel.bottom
 	}
 
-	MouseArea {
-		anchors.fill: parent
-		onClicked: sheetData.updatePixels([pixel])
-	}
-
 }

src/nostalgia/core/studio/Tile.qml

@@ -17,7 +17,12 @@ Rectangle {
 	y: parent.height / 2 - tile.height / 2
 	color: '#000000'
 
+	function pixelAt(x, y) {
+		return tileGrid.childAt(x, y);
+	}
+
 	Grid {
+		id: tileGrid
 		width: tile.width
 		height: tile.height
 		rows: 8

src/nostalgia/core/studio/TileSheetEditor.qml

@@ -13,13 +13,33 @@ Rectangle {
 	id: tileSheetEditor
 	color: '#717d7e'
 
+	MouseArea {
+		id: mouseArea
+		anchors.fill: parent
+		acceptedButtons: Qt.LeftButton
+		onPositionChanged: {
+			var gridX = mouseX - tileGrid.x;
+			var gridY = mouseY - tileGrid.y;
+			var tile = tileGrid.childAt(gridX, gridY);
+			if (tile === null) {
+				return;
+			}
+			var tileX = gridX - tile.x;
+			var tileY = gridY - tile.y;
+			var pixel = tile.pixelAt(tileX, tileY);
+			if (pixel === null) {
+				return;
+			}
+			sheetData.updatePixels([pixel]);
+		}
+
 		Grid {
 			id: tileGrid
 			property int baseTileSize: Math.min(parent.width / tileGrid.columns, parent.height / tileGrid.rows)
 			width: tileGrid.columns * tileGrid.baseTileSize * 0.90
 			height: tileGrid.rows * tileGrid.baseTileSize * 0.90
-		anchors.horizontalCenter: tileSheetEditor.horizontalCenter
+			anchors.horizontalCenter: parent.horizontalCenter
-		anchors.verticalCenter: tileSheetEditor.verticalCenter
+			anchors.verticalCenter: parent.verticalCenter
 			rows: sheetData.rows
 			columns: sheetData.columns
 			Repeater {
@@ -31,5 +51,6 @@ Rectangle {
 				}
 			}
 		}
+	}
 
 }

src/nostalgia/core/studio/tilesheeteditor.cpp

@@ -61,13 +61,15 @@ class UpdatePixelsCommand: public QUndoCommand {
 			m_newColorId = newColorId;
 			cmdIdx = cmdIdx;
 			for (auto &pi : pixelItems) {
-				PixelUpdate pu;
 				auto p = qobject_cast<QQuickItem*>(pi.value<QObject*>());
+				if (p) {
+					PixelUpdate pu;
 					pu.item = p;
 					pu.oldColorId = m_palette.indexOf(p->property("color").toString());
 					m_pixelUpdates.insert(pu);
 				}
 			}
+		}
 
 		virtual ~UpdatePixelsCommand() = default;