Make circle (shift-oval) tool work for any direction dragged (#774)

src/helper/bit-tools/oval-tool.js

@@ -3,6 +3,7 @@ import Modes from '../../lib/modes';
 import {commitOvalToBitmap} from '../bitmap';
 import {getRaster} from '../layer';
 import {clearSelection} from '../selection';
+import {getSquareDimensions} from '../math';
 import BoundingBoxTool from '../selection-tools/bounding-box-tool';
 import NudgeTool from '../selection-tools/nudge-tool';
 
@@ -151,13 +152,17 @@ class OvalTool extends paper.Tool {
 
         const downPoint = new paper.Point(event.downPoint.x, event.downPoint.y);
         const point = new paper.Point(event.point.x, event.point.y);
+        const squareDimensions = getSquareDimensions(event.downPoint, event.point);
         if (event.modifiers.shift) {
-            this.oval.size = new paper.Point(event.downPoint.x - event.point.x, event.downPoint.x - event.point.x);
+            this.oval.size = squareDimensions.size.abs();
         } else {
             this.oval.size = downPoint.subtract(point);
         }
+
         if (event.modifiers.alt) {
             this.oval.position = downPoint;
+        } else if (event.modifiers.shift) {
+            this.oval.position = squareDimensions.position;
         } else {
             this.oval.position = downPoint.subtract(this.oval.size.multiply(0.5));
         }

src/helper/bit-tools/rect-tool.js

@@ -3,6 +3,7 @@ import Modes from '../../lib/modes';
 import {commitRectToBitmap} from '../bitmap';
 import {getRaster} from '../layer';
 import {clearSelection} from '../selection';
+import {getSquareDimensions} from '../math';
 import BoundingBoxTool from '../selection-tools/bounding-box-tool';
 import NudgeTool from '../selection-tools/nudge-tool';
 
@@ -133,10 +134,11 @@ class RectTool extends paper.Tool {
 
         const dimensions = event.point.subtract(event.downPoint);
         const baseRect = new paper.Rectangle(event.downPoint, event.point);
+        const squareDimensions = getSquareDimensions(event.downPoint, event.point);
         if (event.modifiers.shift) {
-            baseRect.height = baseRect.width;
-            dimensions.y = event.downPoint.y > event.point.y ? -Math.abs(baseRect.width) : Math.abs(baseRect.width);
+            baseRect.size = squareDimensions.size.abs();
         }
+
         if (this.rect) this.rect.remove();
         this.rect = new paper.Shape.Rectangle(baseRect);
         if (this.filled) {
@@ -152,6 +154,8 @@ class RectTool extends paper.Tool {
 
         if (event.modifiers.alt) {
             this.rect.position = event.downPoint;
+        } else if (event.modifiers.shift) {
+            this.rect.position = squareDimensions.position;
         } else {
             this.rect.position = event.downPoint.add(dimensions.multiply(.5));
         }

src/helper/math.js

@@ -131,6 +131,39 @@ const scaleWithStrokes = function (root, factor, pivot) {
     root.scale(factor, pivot);
 };
 
+/**
+ * Get the size and position of a square, as in if the user were holding the shift key down while drawing the shape,
+ * from the point where the drag started and the point where the mouse is currently positioned. (Note: This also works
+ * for shapes like circles ("square ovals"), which fill the same dimensions.)
+ * @param {!paper.Point} startPos The point where the user started dragging
+ * @param {!paper.Point} eventPoint The point where the user has currently dragged to
+ * @return {object} Information about the size and position of how the square should be drawn
+ */
+const getSquareDimensions = function (startPos, eventPoint) {
+    // These variables are used for determining the relative quadrant that the shape will appear in.
+    // So if you drag up and right, it'll show up above and to the right of where you started dragging, etc.
+    let offsetX = eventPoint.x - startPos.x;
+    let offsetY = eventPoint.y - startPos.y;
+
+    // If the offset variables are zero, the shape ends up having zero width or height, which is bad.
+    // Deal with this by forcing them to be non-zero (we arbitrarily choose 1; any non-zero value would work).
+    offsetX = offsetX ? offsetX : 1;
+    offsetY = offsetY ? offsetY : 1;
+
+    // The length of the shape is the greater of the X and Y offsets.
+    const offsetDistance = eventPoint.subtract(startPos).abs();
+    const length = Math.max(offsetDistance.x, offsetDistance.y);
+
+    const size = new paper.Point(
+        length * offsetX / Math.abs(offsetX),
+        length * offsetY / Math.abs(offsetY)
+    );
+
+    const position = startPos.add(size.multiply(0.5));
+
+    return {size, position};
+};
+
 export {
     HANDLE_RATIO,
     checkPointsClose,
@@ -138,6 +171,7 @@ export {
     expandBy,
     getRandomInt,
     getRandomBoolean,
+    getSquareDimensions,
     scaleWithStrokes,
     snapDeltaToAngle,
     sortItemsByZIndex

src/helper/tools/oval-tool.js

@@ -2,6 +2,7 @@ import paper from '@scratch/paper';
 import Modes from '../../lib/modes';
 import {styleShape} from '../style-path';
 import {clearSelection} from '../selection';
+import {getSquareDimensions} from '../math';
 import BoundingBoxTool from '../selection-tools/bounding-box-tool';
 import NudgeTool from '../selection-tools/nudge-tool';
 
@@ -88,17 +89,20 @@ class OvalTool extends paper.Tool {
 
         const downPoint = new paper.Point(event.downPoint.x, event.downPoint.y);
         const point = new paper.Point(event.point.x, event.point.y);
+        const squareDimensions = getSquareDimensions(event.downPoint, event.point);
         if (event.modifiers.shift) {
-            this.oval.size = new paper.Point(event.downPoint.x - event.point.x, event.downPoint.x - event.point.x);
+            this.oval.size = squareDimensions.size.abs();
         } else {
             this.oval.size = downPoint.subtract(point);
         }
+
         if (event.modifiers.alt) {
             this.oval.position = downPoint;
+        } else if (event.modifiers.shift) {
+            this.oval.position = squareDimensions.position;
         } else {
             this.oval.position = downPoint.subtract(this.oval.size.multiply(0.5));
         }
-
     }
     handleMouseUp (event) {
         if (event.event.button > 0 || !this.active) return; // only first mouse button

src/helper/tools/rect-tool.js

@@ -2,6 +2,7 @@ import paper from '@scratch/paper';
 import Modes from '../../lib/modes';
 import {styleShape} from '../style-path';
 import {clearSelection} from '../selection';
+import {getSquareDimensions} from '../math';
 import BoundingBoxTool from '../selection-tools/bounding-box-tool';
 import NudgeTool from '../selection-tools/nudge-tool';
 
@@ -85,18 +86,20 @@ class RectTool extends paper.Tool {
             this.rect.remove();
         }
 
-        const dimensions = event.point.subtract(event.downPoint);
         const rect = new paper.Rectangle(event.downPoint, event.point);
+        const squareDimensions = getSquareDimensions(event.downPoint, event.point);
         if (event.modifiers.shift) {
-            rect.height = rect.width;
-            dimensions.y = event.downPoint.y > event.point.y ? -Math.abs(rect.width) : Math.abs(rect.width);
+            rect.size = squareDimensions.size.abs();
         }
-        this.rect = new paper.Path.Rectangle(rect);
 
+        this.rect = new paper.Path.Rectangle(rect);
         if (event.modifiers.alt) {
             this.rect.position = event.downPoint;
+        } else if (event.modifiers.shift) {
+            this.rect.position = squareDimensions.position;
         } else {
-            this.rect.position = event.downPoint.add(dimensions.multiply(.5));
+            const dimensions = event.point.subtract(event.downPoint);
+            this.rect.position = event.downPoint.add(dimensions.multiply(0.5));
         }
 
         styleShape(this.rect, this.colorState);