path: root/javascript/zoom.js

// Main
onUiLoaded(async () => {
  const hotkeysConfig = {
    resetZoom: "KeyR",
    fitToScreen: "KeyS",
    moveKey: "KeyF",
    overlap: "KeyO",
  };

  let isMoving = false;
  let mouseX, mouseY;

  const elementIDs = {
    sketch: "#img2img_sketch",
    inpaint: "#img2maskimg",
    inpaintSketch: "#inpaint_sketch",
    img2imgTabs: "#mode_img2img .tab-nav",
  };

  async function getElements() {
    const elements = await Promise.all(
      Object.values(elementIDs).map((id) => document.querySelector(id))
    );
    return Object.fromEntries(
      Object.keys(elementIDs).map((key, index) => [key, elements[index]])
    );
  }

  const elements = await getElements();

  function applyZoomAndPan(targetElement, elemId) {
    targetElement.style.transformOrigin = "0 0";
    let [zoomLevel, panX, panY] = [1, 0, 0];
    let fullScreenMode = false;

    // Reset the zoom level and pan position of the target element to their initial values
    function resetZoom() {
      zoomLevel = 1;
      panX = 0;
      panY = 0;

      targetElement.style.transform = `scale(${zoomLevel}) translate(${panX}px, ${panY}px)`;

      const canvas = document.querySelector(`${elemId} canvas[key="interface"]`);

      toggleOverlap("off");
      fullScreenMode = false;

      targetElement.style.width = "";
      if (canvas) {
        targetElement.style.height = canvas.style.height;
      }
    }

    // Toggle the zIndex of the target element between two values, allowing it to overlap or be overlapped by other elements
    function toggleOverlap(forced = "") {
      const zIndex1 = "0";
      const zIndex2 = "998";

      targetElement.style.zIndex =
        targetElement.style.zIndex !== zIndex2 ? zIndex2 : zIndex1;

      if (forced === "off") {
        targetElement.style.zIndex = zIndex1;
      } else if (forced === "on") {
        targetElement.style.zIndex = zIndex2;
      }
    }

    // Adjust the brush size based on the deltaY value from a mouse wheel event
    function adjustBrushSize(
      elemId,
      deltaY,
      withoutValue = false,
      percentage = 5
    ) {
      const input =
        document.querySelector(`${elemId} input[aria-label='Brush radius']`) ||
        document.querySelector(`${elemId} button[aria-label="Use brush"]`);

      if (input) {
        input.click();
        if (!withoutValue) {
          const maxValue = parseFloat(input.getAttribute("max")) || 100;
          const changeAmount = maxValue * (percentage / 100);
          const newValue =
            parseFloat(input.value) +
            (deltaY > 0 ? -changeAmount : changeAmount);
          input.value = Math.min(Math.max(newValue, 0), maxValue);
          input.dispatchEvent(new Event("change"));
        }
      }
    }

    // Reset zoom when uploading a new image
    fileInput = document.querySelector(
      `${elemId} input[type="file"][accept="image/*"].svelte-116rqfv`
    );
    fileInput.addEventListener("click", resetZoom);

    // Update the zoom level and pan position of the target element based on the values of the zoomLevel, panX and panY variables
    function updateZoom(newZoomLevel, mouseX, mouseY) {
      newZoomLevel = Math.max(0.5, Math.min(newZoomLevel, 15));
      panX += mouseX - (mouseX * newZoomLevel) / zoomLevel;
      panY += mouseY - (mouseY * newZoomLevel) / zoomLevel;

      targetElement.style.transformOrigin = "0 0";
      targetElement.style.transform = `translate(${panX}px, ${panY}px) scale(${newZoomLevel})`;

      toggleOverlap("on");
      return newZoomLevel;
    }

    // Change the zoom level based on user interaction
    function changeZoomLevel(operation, e) {
      if (e.shiftKey) {
        e.preventDefault();

        let zoomPosX, zoomPosY;
        let delta = 0.2;
        if (zoomLevel > 7) {
          delta = 0.9;
        } else if (zoomLevel > 2) {
          delta = 0.6;
        }

        zoomPosX = e.clientX;
        zoomPosY = e.clientY;

        fullScreenMode = false;
        zoomLevel = updateZoom(
          zoomLevel + (operation === "+" ? delta : -delta),
          zoomPosX - targetElement.getBoundingClientRect().left,
          zoomPosY - targetElement.getBoundingClientRect().top
        );
      }
    }

    /**
       * This function fits the target element to the screen by calculating
       * the required scale and offsets. It also updates the global variables
       * zoomLevel, panX, and panY to reflect the new state.
       */

    // Fullscreen mode
    function fitToScreen() {
      const canvas = document.querySelector(`${elemId} canvas[key="interface"]`);

      if (!canvas) return;

      if (fullScreenMode) {
        resetZoom();
        fullScreenMode = false;
        return;
      }

      resetZoom();

      // Get element and screen dimensions
      const elementWidth = targetElement.offsetWidth;
      const elementHeight = targetElement.offsetHeight;
      const screenWidth = window.innerWidth;
      const screenHeight = window.innerHeight;

      // Get element's coordinates relative to the page
      const elementRect = targetElement.getBoundingClientRect();
      const elementY = elementRect.y;
      const elementX = elementRect.x;

      // Calculate scale and offsets
      const scaleX = screenWidth / elementWidth;
      const scaleY = screenHeight / elementHeight;
      const scale = Math.min(scaleX, scaleY);

      // Get the current transformOrigin
      const computedStyle = window.getComputedStyle(targetElement);
      const transformOrigin = computedStyle.transformOrigin;
      const [originX, originY] = transformOrigin.split(" ");
      const originXValue = parseFloat(originX);
      const originYValue = parseFloat(originY);

      // Calculate offsets with respect to the transformOrigin
      const offsetX = (screenWidth - elementWidth * scale) / 2 - elementX - originXValue * (1 - scale);
      const offsetY = (screenHeight - elementHeight * scale) / 2 - elementY - originYValue * (1 - scale);

      // Apply scale and offsets to the element
      targetElement.style.transform = `translate(${offsetX}px, ${offsetY}px) scale(${scale})`;

      // Update global variables
      zoomLevel = scale;
      panX = offsetX;
      panY = offsetY;

      toggleOverlap("on");
      fullScreenMode = true;
    }

    // Handle keydown events
    function handleKeyDown(event) {
      const hotkeyActions = {
        [hotkeysConfig.resetZoom]: resetZoom,
        [hotkeysConfig.overlap]: toggleOverlap,
        [hotkeysConfig.fitToScreen]: fitToScreen,
        // [hotkeysConfig.moveKey] : moveCanvas,
      };

      const action = hotkeyActions[event.code];
      if (action) {
        event.preventDefault();
        action(event);
      } 

    }

    // Get Mouse position
    function getMousePosition(e) {
      mouseX = e.offsetX;
      mouseY = e.offsetY;
    }

    targetElement.addEventListener("mousemove", getMousePosition);

    // Handle events only inside the targetElement
    let isKeyDownHandlerAttached = false;

    function handleMouseMove() {
      if (!isKeyDownHandlerAttached) {
        document.addEventListener("keydown", handleKeyDown);
        isKeyDownHandlerAttached = true;
      }
    }

    function handleMouseLeave() {
      if (isKeyDownHandlerAttached) {
        document.removeEventListener("keydown", handleKeyDown);
        isKeyDownHandlerAttached = false;
      }
    }

    // Add mouse event handlers
    targetElement.addEventListener("mousemove", handleMouseMove);
    targetElement.addEventListener("mouseleave", handleMouseLeave);

    // Reset zoom when click on another tab
    elements.img2imgTabs.addEventListener("click", resetZoom);

    targetElement.addEventListener("wheel", (e) => {
      // change zoom level
      const operation = e.deltaY > 0 ? "-" : "+";
      changeZoomLevel(operation, e);

      // Handle brush size adjustment with ctrl key pressed
      if (e.ctrlKey || e.metaKey) {
        e.preventDefault();

        // Increase or decrease brush size based on scroll direction
        adjustBrushSize(elemId, e.deltaY);
      }
    });

    /**
       * Handle the move event for pan functionality. Updates the panX and panY variables and applies the new transform to the target element.
       * @param {MouseEvent} e - The mouse event.
       */
    function handleMoveKeyDown(e) {
      if (e.code === hotkeysConfig.moveKey) {
        if(!e.ctrlKey  && !e.metaKey){
          isMoving = true;
        }
      }
    }

    function handleMoveKeyUp(e) {
      if (e.code === hotkeysConfig.moveKey) {
        isMoving = false;
      }
    }

    document.addEventListener("keydown", handleMoveKeyDown);
    document.addEventListener("keyup", handleMoveKeyUp);

    // Detect zoom level and update the pan speed.
    function updatePanPosition(movementX, movementY) {
      let panSpeed = 1.5;

      if (zoomLevel > 8) {
        panSpeed = 2.5;
      }

      panX = panX + movementX * panSpeed;
      panY = panY + movementY * panSpeed;

      targetElement.style.transform = `translate(${panX}px, ${panY}px) scale(${zoomLevel})`;
      toggleOverlap("on");
    }

    function handleMoveByKey(e) {
      if (isMoving) {
        updatePanPosition(e.movementX, e.movementY);
        targetElement.style.pointerEvents = "none";
      } else {
        targetElement.style.pointerEvents = "auto";
      }
    }

    document.addEventListener("mousemove", handleMoveByKey);
  }

  applyZoomAndPan(elements.sketch, elementIDs.sketch);
  applyZoomAndPan(elements.inpaint, elementIDs.inpaint);
  applyZoomAndPan(elements.inpaintSketch, elementIDs.inpaintSketch);
});