sdnext/javascript/dragdrop.js

// allows drag-dropping files into gradio image elements, and also pasting images from clipboard

function isValidImageList(files) {
  return files && files?.length === 1 && ['image/png', 'image/gif', 'image/jpeg'].includes(files[0].type);
}

function dropReplaceImage(imgWrap, files) {
  if (!isValidImageList(files)) return;
  const tmpFile = files[0];
  imgWrap.querySelector('.modify-upload button + button, .touch-none + div button + button')?.click();
  const callback = () => {
    const fileInput = imgWrap.querySelector('input[type="file"]');
    if (fileInput) {
      if (files.length === 0) {
        files = new DataTransfer();
        files.items.add(tmpFile);
        fileInput.files = files.files;
      } else {
        fileInput.files = files;
      }
      fileInput.dispatchEvent(new Event('change'));
    }
  };

  if (imgWrap.closest('#pnginfo_image')) {
    // special treatment for PNG Info tab, wait for fetch request to finish
    const oldFetch = window.fetch;
    window.fetch = async (input, options) => {
      const response = await oldFetch(input, options);
      if (input === 'api/predict/') {
        const content = await response.text();
        window.fetch = oldFetch;
        window.requestAnimationFrame(() => callback());
        return new Response(content, {
          status: response.status,
          statusText: response.statusText,
          headers: response.headers,
        });
      }
      return response;
    };
  } else {
    window.requestAnimationFrame(() => callback());
  }
}

window.document.addEventListener('dragover', (e) => {
  const target = e.composedPath()[0];
  const imgWrap = target.closest('[data-testid="image"]');
  if (!imgWrap && target.placeholder && target.placeholder.indexOf('Prompt') === -1) return;
  e.stopPropagation();
  e.preventDefault();
  e.dataTransfer.dropEffect = 'copy';
});

window.document.addEventListener('drop', (e) => {
  const target = e.composedPath()[0];
  if (!target.placeholder) return;
  if (target.placeholder.indexOf('Prompt') === -1) return;
  const imgWrap = target.closest('[data-testid="image"]');
  if (!imgWrap) return;
  e.stopPropagation();
  e.preventDefault();
  const { files } = e.dataTransfer;
  dropReplaceImage(imgWrap, files);
});

window.addEventListener('paste', (e) => {
  const { files } = e.clipboardData;
  if (!isValidImageList(files)) return;
  const visibleImageFields = [...gradioApp().querySelectorAll('[data-testid="image"]')].filter((el) => uiElementIsVisible(el));
  if (!visibleImageFields.length) return;
  const firstFreeImageField = visibleImageFields.filter((el) => el.querySelector('input[type=file]'))?.[0];
  dropReplaceImage(firstFreeImageField || visibleImageFields[visibleImageFields.length - 1], files);
});