manipulate and update a crop

packages/excalidraw/components/App.tsx

@@ -441,7 +441,14 @@ import {
   getLinkDirectionFromKey,
 } from "../element/flowchart";
 import type { LocalPoint, Radians } from "../../math";
-import { point, pointDistance, vector } from "../../math";
+import {
+  clamp,
+  point,
+  pointDistance,
+  pointRotateRads,
+  vector,
+} from "../../math";
+import { cropElement } from "../element/cropElement";
 
 const AppContext = React.createContext<AppClassProperties>(null!);
 const AppPropsContext = React.createContext<AppProps>(null!);
@@ -584,6 +591,7 @@ class App extends React.Component<AppProps, AppState> {
   lastPointerUpEvent: React.PointerEvent<HTMLElement> | PointerEvent | null =
     null;
   lastPointerMoveEvent: PointerEvent | null = null;
+  lastPointerMoveCoords: { x: number; y: number } | null = null;
   lastViewportPosition = { x: 0, y: 0 };
 
   animationFrameHandler = new AnimationFrameHandler();
@@ -3862,6 +3870,28 @@ class App extends React.Component<AppProps, AppState> {
       }
 
       if (!isInputLike(event.target)) {
+        if (
+          (event.key === KEYS.ESCAPE || event.key === KEYS.ENTER) &&
+          this.state.croppingElement
+        ) {
+          this.finishImageCropping();
+          return;
+        }
+
+        const selectedElements = getSelectedElements(
+          this.scene.getNonDeletedElementsMap(),
+          this.state,
+        );
+
+        if (
+          selectedElements.length === 1 &&
+          isImageElement(selectedElements[0]) &&
+          event.key === KEYS.ENTER
+        ) {
+          this.startImageCropping(selectedElements[0]);
+          return;
+        }
+
         if (
           event.key === KEYS.ESCAPE &&
           this.flowChartCreator.isCreatingChart
@@ -6560,6 +6590,12 @@ class App extends React.Component<AppProps, AppState> {
         arrowDirection: "origin",
         center: { x: (maxX + minX) / 2, y: (maxY + minY) / 2 },
       },
+      crop: {
+        handleType: false,
+        isCropping: false,
+        offset: { x: 0, y: 0 },
+        complete: false,
+      },
       hit: {
         element: null,
         allHitElements: [],
@@ -6671,12 +6707,29 @@ class App extends React.Component<AppProps, AppState> {
             this.device,
           );
         if (elementWithTransformHandleType != null) {
+          if (
+            elementWithTransformHandleType.transformHandleType === "rotation"
+          ) {
+            this.setState({
+              resizingElement: elementWithTransformHandleType.element,
+            });
+            pointerDownState.resize.handleType =
+              elementWithTransformHandleType.transformHandleType;
+          } else if (this.state.croppingElement) {
+            this.setState({
+              croppingElement:
+                elementWithTransformHandleType.element as ExcalidrawImageElement,
+            });
+            pointerDownState.crop.handleType =
+              elementWithTransformHandleType.transformHandleType;
+          } else {
             this.setState({
               resizingElement: elementWithTransformHandleType.element,
             });
             pointerDownState.resize.handleType =
               elementWithTransformHandleType.transformHandleType;
           }
+        }
       } else if (selectedElements.length > 1) {
         pointerDownState.resize.handleType = getTransformHandleTypeFromCoords(
           getCommonBounds(selectedElements),
@@ -6708,6 +6761,17 @@ class App extends React.Component<AppProps, AppState> {
             selectedElements[0],
           );
         }
+      } else if (pointerDownState.crop.handleType) {
+        pointerDownState.crop.isCropping = true;
+        pointerDownState.crop.offset = tupleToCoors(
+          getResizeOffsetXY(
+            pointerDownState.crop.handleType,
+            selectedElements,
+            this.scene.getNonDeletedElementsMap(),
+            pointerDownState.origin.x,
+            pointerDownState.origin.y,
+          ),
+        );
       } else {
         if (this.state.selectedLinearElement) {
           const linearElementEditor =
@@ -7604,6 +7668,13 @@ class App extends React.Component<AppProps, AppState> {
           return true;
         }
       }
+      if (pointerDownState.crop.isCropping) {
+        pointerDownState.lastCoords.x = pointerCoords.x;
+        pointerDownState.lastCoords.y = pointerCoords.y;
+        if (this.maybeHandleCrop(pointerDownState, event)) {
+          return true;
+        }
+      }
       const elementsMap = this.scene.getNonDeletedElementsMap();
 
       if (this.state.selectedLinearElement) {
@@ -7773,6 +7844,65 @@ class App extends React.Component<AppProps, AppState> {
             }
           }
 
+          // #region drag
+          if (
+            selectedElements.length === 1 &&
+            isImageElement(selectedElements[0]) &&
+            this.state.croppingElement?.id === selectedElements[0].id &&
+            selectedElements[0].crop !== null
+          ) {
+            const crop = selectedElements[0].crop;
+            const image = selectedElements[0];
+
+            const lastPointerCoords =
+              this.lastPointerMoveCoords ?? pointerDownState.origin;
+
+            const instantDragOffset = {
+              x: pointerCoords.x - lastPointerCoords.x,
+              y: pointerCoords.y - lastPointerCoords.y,
+            };
+
+            // current offset is based on the element's width and height
+            const uncroppedWidth = image.widthAtCreation * image.resizedFactorX;
+            const uncroppedHeight =
+              image.heightAtCreation * image.resizedFactorY;
+
+            const SENSITIVITY_FACTOR = 3;
+
+            const adjustedOffset = {
+              x:
+                instantDragOffset.x *
+                (uncroppedWidth / image.naturalWidth) *
+                SENSITIVITY_FACTOR,
+              y:
+                instantDragOffset.y *
+                (uncroppedHeight / image.naturalHeight) *
+                SENSITIVITY_FACTOR,
+            };
+
+            const nextCrop = {
+              ...crop,
+              x: clamp(
+                crop.x - adjustedOffset.x,
+                0,
+                image.naturalWidth - crop.width,
+              ),
+              y: clamp(
+                crop.y - adjustedOffset.y,
+                0,
+                image.naturalHeight - crop.height,
+              ),
+            };
+
+            mutateElement(image, {
+              crop: nextCrop,
+            });
+
+            this.lastPointerMoveCoords = pointerCoords;
+
+            return;
+          }
+
           // Snap cache *must* be synchronously popuplated before initial drag,
           // otherwise the first drag even will not snap, causing a jump before
           // it snaps to its position if previously snapped already.
@@ -7906,6 +8036,8 @@ class App extends React.Component<AppProps, AppState> {
             this.maybeCacheVisibleGaps(event, selectedElements, true);
             this.maybeCacheReferenceSnapPoints(event, selectedElements, true);
           }
+
+          this.lastPointerMoveCoords = pointerCoords;
           return;
         }
       }
@@ -8158,6 +8290,7 @@ class App extends React.Component<AppProps, AppState> {
         activeTool,
         isResizing,
         isRotating,
+        isCropping,
       } = this.state;
 
       this.setState((prevState) => ({
@@ -8172,6 +8305,8 @@ class App extends React.Component<AppProps, AppState> {
         originSnapOffset: null,
       }));
 
+      this.lastPointerMoveCoords = null;
+
       SnapCache.setReferenceSnapPoints(null);
       SnapCache.setVisibleGaps(null);
 
@@ -8654,6 +8789,15 @@ class App extends React.Component<AppProps, AppState> {
         }
       }
 
+      if (
+        isCropping &&
+        !isResizing &&
+        ((!hitElement && !pointerDownState.crop.isCropping) ||
+          (hitElement && hitElement !== this.state.croppingElement))
+      ) {
+        this.finishImageCropping();
+      }
+
       const pointerStart = this.lastPointerDownEvent;
       const pointerEnd = this.lastPointerUpEvent || this.lastPointerMoveEvent;
 
@@ -8909,7 +9053,12 @@ class App extends React.Component<AppProps, AppState> {
         this.store.shouldCaptureIncrement();
       }
 
-      if (pointerDownState.drag.hasOccurred || isResizing || isRotating) {
+      if (
+        pointerDownState.drag.hasOccurred ||
+        isResizing ||
+        isRotating ||
+        isCropping
+      ) {
         // We only allow binding via linear elements, specifically via dragging
         // the endpoints ("start" or "end").
         const linearElements = this.scene
@@ -9324,7 +9473,18 @@ class App extends React.Component<AppProps, AppState> {
       const x = imageElement.x + imageElement.width / 2 - width / 2;
       const y = imageElement.y + imageElement.height / 2 - height / 2;
 
-      mutateElement(imageElement, { x, y, width, height });
+      mutateElement(imageElement, {
+        x,
+        y,
+        width,
+        height,
+        widthAtCreation: width,
+        heightAtCreation: height,
+        naturalWidth: image.naturalWidth,
+        naturalHeight: image.naturalHeight,
+        resizedFactorX: 1,
+        resizedFactorY: 1,
+      });
     }
   };
 
@@ -9863,6 +10023,46 @@ class App extends React.Component<AppProps, AppState> {
     }
   };
 
+  private maybeHandleCrop = (
+    pointerDownState: PointerDownState,
+    event: MouseEvent | KeyboardEvent,
+  ): boolean => {
+    if (pointerDownState.crop.complete) {
+      return true;
+    }
+    const selectedElements = getSelectedElements(
+      this.scene.getNonDeletedElements(),
+      this.state,
+    );
+
+    if (selectedElements.length > 1) {
+      // don't see much sense in allowing multi-crop, that would be weird
+      return false;
+    }
+
+    const transformHandleType = pointerDownState.crop.handleType;
+    const pointerCoords = pointerDownState.lastCoords;
+    const [x, y] = getGridPoint(
+      pointerCoords.x - pointerDownState.crop.offset.x,
+      pointerCoords.y - pointerDownState.crop.offset.y,
+      this.getEffectiveGridSize(),
+    );
+
+    const elementToCrop = selectedElements[0] as ExcalidrawImageElement;
+    if (transformHandleType) {
+      cropElement(
+        elementToCrop,
+        this.scene.getNonDeletedElementsMap(),
+        transformHandleType,
+        x,
+        y,
+      );
+      return true;
+    }
+
+    return false;
+  };
+
   private maybeHandleResize = (
     pointerDownState: PointerDownState,
     event: MouseEvent | KeyboardEvent,

packages/excalidraw/element/cropElement.ts

@@ -0,0 +1,292 @@
+import { Point } from "points-on-curve";
+import {
+  type Radians,
+  point,
+  pointCenter,
+  pointRotateRads,
+  vectorFromPoint,
+  vectorNormalize,
+  vectorSubtract,
+  vectorAdd,
+  vectorScale,
+  pointFromVector,
+  clamp,
+} from "../../math";
+import { updateBoundElements } from "./binding";
+import { mutateElement } from "./mutateElement";
+import { TransformHandleType } from "./transformHandles";
+import {
+  ElementsMap,
+  ExcalidrawElement,
+  ExcalidrawImageElement,
+  NonDeleted,
+  NonDeletedSceneElementsMap,
+} from "./types";
+import {
+  getElementAbsoluteCoords,
+  getResizedElementAbsoluteCoords,
+} from "./bounds";
+
+// i split out these 'internal' functions so that this functionality can be easily unit tested
+const cropElementInternal = (
+  element: ExcalidrawImageElement,
+  transformHandle: TransformHandleType,
+  pointerX: number,
+  pointerY: number,
+) => {
+  const uncroppedWidth = element.widthAtCreation * element.resizedFactorX;
+  const uncroppedHeight = element.heightAtCreation * element.resizedFactorY;
+
+  const naturalWidthToUncropped = element.naturalWidth / uncroppedWidth;
+  const naturalHeightToUncropped = element.naturalHeight / uncroppedHeight;
+
+  const croppedLeft = (element.crop?.x ?? 0) / naturalWidthToUncropped;
+  const croppedTop = (element.crop?.y ?? 0) / naturalHeightToUncropped;
+
+  /**
+   * uncropped width
+   * *––––––––––––––––––––––––*
+   * |     (x,y) (natural)    |
+   * |       *–––––––*        |
+   * |       |///////| height | uncropped height
+   * |       *–––––––*        |
+   * |    width (natural)     |
+   * *––––––––––––––––––––––––*
+   */
+
+  const availableTopCropSpace = croppedTop;
+  const availableLeftCropSpace = croppedLeft;
+
+  const rotatedPointer = pointRotateRads(
+    point(pointerX, pointerY),
+    point(element.x + element.width / 2, element.y + element.height / 2),
+    -element.angle as Radians,
+  );
+
+  pointerX = rotatedPointer[0];
+  pointerY = rotatedPointer[1];
+
+  let nextWidth = element.width;
+  let nextHeight = element.height;
+  const crop = element.crop ?? {
+    x: 0,
+    y: 0,
+    width: element.naturalWidth,
+    height: element.naturalHeight,
+  };
+
+  if (transformHandle.includes("n")) {
+    const northBound = element.y - availableTopCropSpace;
+    const southBound = element.y + element.height;
+
+    pointerY = clamp(pointerY, northBound, southBound);
+
+    const pointerDeltaY = pointerY - element.y;
+    nextHeight = element.height - pointerDeltaY;
+
+    crop.y =
+      ((pointerDeltaY + croppedTop) / uncroppedHeight) * element.naturalHeight;
+    crop.height = (nextHeight / uncroppedHeight) * element.naturalHeight;
+  }
+
+  if (transformHandle.includes("s")) {
+    const northBound = element.y;
+    const southBound = element.y + (uncroppedHeight - croppedTop);
+
+    pointerY = clamp(pointerY, northBound, southBound);
+
+    nextHeight = pointerY - element.y;
+    crop.height = (nextHeight / uncroppedHeight) * element.naturalHeight;
+  }
+
+  if (transformHandle.includes("w")) {
+    const eastBound = element.x + element.width;
+    const westBound = element.x - availableLeftCropSpace;
+
+    pointerX = clamp(pointerX, westBound, eastBound);
+
+    const pointerDeltaX = pointerX - element.x;
+    nextWidth = element.width - pointerDeltaX;
+
+    crop.x =
+      ((pointerDeltaX + croppedLeft) / uncroppedWidth) * element.naturalWidth;
+    crop.width = (nextWidth / uncroppedWidth) * element.naturalWidth;
+  }
+
+  if (transformHandle.includes("e")) {
+    const eastBound = element.x + (uncroppedWidth - croppedLeft);
+    const westBound = element.x;
+
+    pointerX = clamp(pointerX, westBound, eastBound);
+
+    nextWidth = pointerX - element.x;
+    crop.width = (nextWidth / uncroppedWidth) * element.naturalWidth;
+  }
+
+  const newOrigin = recomputeOrigin(
+    element,
+    transformHandle,
+    nextWidth,
+    nextHeight,
+  );
+
+  return {
+    x: newOrigin[0],
+    y: newOrigin[1],
+    width: nextWidth,
+    height: nextHeight,
+    crop,
+  };
+};
+
+export const cropElement = (
+  element: ExcalidrawImageElement,
+  elementsMap: NonDeletedSceneElementsMap,
+  transformHandle: TransformHandleType,
+  pointerX: number,
+  pointerY: number,
+) => {
+  const mutation = cropElementInternal(
+    element,
+    transformHandle,
+    pointerX,
+    pointerY,
+  );
+
+  mutateElement(element, mutation);
+
+  updateBoundElements(element, elementsMap, {
+    oldSize: { width: element.width, height: element.height },
+  });
+};
+
+// TODO: replace with the refactored resizeSingleElement
+const recomputeOrigin = (
+  stateAtCropStart: NonDeleted<ExcalidrawElement>,
+  transformHandle: TransformHandleType,
+  width: number,
+  height: number,
+) => {
+  const [x1, y1, x2, y2] = getResizedElementAbsoluteCoords(
+    stateAtCropStart,
+    stateAtCropStart.width,
+    stateAtCropStart.height,
+    true,
+  );
+  const startTopLeft = point(x1, y1);
+  const startBottomRight = point(x2, y2);
+  const startCenter: any = pointCenter(startTopLeft, startBottomRight);
+
+  const [newBoundsX1, newBoundsY1, newBoundsX2, newBoundsY2] =
+    getResizedElementAbsoluteCoords(stateAtCropStart, width, height, true);
+  const newBoundsWidth = newBoundsX2 - newBoundsX1;
+  const newBoundsHeight = newBoundsY2 - newBoundsY1;
+
+  // Calculate new topLeft based on fixed corner during resize
+  let newTopLeft = [...startTopLeft] as [number, number];
+
+  if (["n", "w", "nw"].includes(transformHandle)) {
+    newTopLeft = [
+      startBottomRight[0] - Math.abs(newBoundsWidth),
+      startBottomRight[1] - Math.abs(newBoundsHeight),
+    ];
+  }
+  if (transformHandle === "ne") {
+    const bottomLeft = [startTopLeft[0], startBottomRight[1]];
+    newTopLeft = [bottomLeft[0], bottomLeft[1] - Math.abs(newBoundsHeight)];
+  }
+  if (transformHandle === "sw") {
+    const topRight = [startBottomRight[0], startTopLeft[1]];
+    newTopLeft = [topRight[0] - Math.abs(newBoundsWidth), topRight[1]];
+  }
+
+  // adjust topLeft to new rotation point
+  const angle = stateAtCropStart.angle;
+  const rotatedTopLeft = pointRotateRads(newTopLeft, startCenter, angle);
+  const newCenter: Point = [
+    newTopLeft[0] + Math.abs(newBoundsWidth) / 2,
+    newTopLeft[1] + Math.abs(newBoundsHeight) / 2,
+  ];
+  const rotatedNewCenter = pointRotateRads(newCenter, startCenter, angle);
+  newTopLeft = pointRotateRads(
+    rotatedTopLeft,
+    rotatedNewCenter,
+    -angle as Radians,
+  );
+
+  const newOrigin = [...newTopLeft];
+  newOrigin[0] += stateAtCropStart.x - newBoundsX1;
+  newOrigin[1] += stateAtCropStart.y - newBoundsY1;
+
+  return newOrigin;
+};
+
+export const getUncroppedImageElement = (
+  image: ExcalidrawImageElement,
+  elementsMap: ElementsMap,
+) => {
+  if (image.crop) {
+    const width = image.widthAtCreation * image.resizedFactorX;
+    const height = image.heightAtCreation * image.resizedFactorY;
+
+    const [x1, y1, x2, y2, cx, cy] = getElementAbsoluteCoords(
+      image,
+      elementsMap,
+    );
+
+    const topLeftVector = vectorFromPoint(
+      pointRotateRads(point(x1, y1), point(cx, cy), image.angle),
+    );
+    const topRightVector = vectorFromPoint(
+      pointRotateRads(point(x2, y1), point(cx, cy), image.angle),
+    );
+    const topEdgeNormalized = vectorNormalize(
+      vectorSubtract(topRightVector, topLeftVector),
+    );
+    const bottomLeftVector = vectorFromPoint(
+      pointRotateRads(point(x1, y2), point(cx, cy), image.angle),
+    );
+    const leftEdgeVector = vectorSubtract(bottomLeftVector, topLeftVector);
+    const leftEdgeNormalized = vectorNormalize(leftEdgeVector);
+
+    const rotatedTopLeft = vectorAdd(
+      vectorAdd(
+        topLeftVector,
+        vectorScale(
+          topEdgeNormalized,
+          (-image.crop.x * width) / image.naturalWidth,
+        ),
+      ),
+      vectorScale(
+        leftEdgeNormalized,
+        (-image.crop.y * height) / image.naturalHeight,
+      ),
+    );
+
+    const center = pointFromVector(
+      vectorAdd(
+        vectorAdd(rotatedTopLeft, vectorScale(topEdgeNormalized, width / 2)),
+        vectorScale(leftEdgeNormalized, height / 2),
+      ),
+    );
+
+    const unrotatedTopLeft = pointRotateRads(
+      pointFromVector(rotatedTopLeft),
+      center,
+      -image.angle as Radians,
+    );
+
+    const uncroppedElement: ExcalidrawImageElement = {
+      ...image,
+      x: unrotatedTopLeft[0],
+      y: unrotatedTopLeft[1],
+      width,
+      height,
+      crop: null,
+    };
+
+    return uncroppedElement;
+  }
+
+  return image;
+};

packages/excalidraw/element/resizeElements.ts

@@ -696,6 +696,13 @@ export const resizeSingleElement = (
     points: rescaledPoints,
   };
 
+  // TODO: this is not the best approach
+  updateInternalScale(
+    element,
+    eleNewWidth / element.width,
+    eleNewHeight / element.height,
+  );
+
   if ("scale" in element && "scale" in stateAtResizeStart) {
     mutateElement(element, {
       scale: [
@@ -750,6 +757,36 @@ export const resizeSingleElement = (
   }
 };
 
+const updateInternalScale = (
+  element: NonDeletedExcalidrawElement,
+  scaleX: number,
+  scaleY: number,
+) => {
+  if ("type" in element && element.type === "image") {
+    element = element as ExcalidrawImageElement;
+  } else {
+    return;
+  }
+
+  // if the scales happen to be 0 (which is insanely unlikely), it will
+  // zero out the rolling multiplier and cause weird bugs with cropping.
+  // if zero is detected, just set the scales to an obnoxiously small number
+  if (scaleX === 0) {
+    scaleX = Number.EPSILON;
+  }
+  if (scaleY === 0) {
+    scaleY = Number.EPSILON;
+  }
+
+  scaleX = Math.abs(scaleX);
+  scaleY = Math.abs(scaleY);
+
+  mutateElement(element, {
+    resizedFactorX: element.resizedFactorX * scaleX,
+    resizedFactorY: element.resizedFactorY * scaleY,
+  });
+};
+
 export const resizeMultipleElements = (
   originalElements: PointerDownState["originalElements"],
   selectedElements: readonly NonDeletedExcalidrawElement[],