Function _initScreenshots

apps/screenshot/content-script.js:79–125

* 初始化截图canvas * @param {number} totalWidth - 总宽度 * @param {number} totalHeight - 总高度 * @returns {Array} - 初始化的canvas数组 * @private

(totalWidth, totalHeight)

     * @private
     */
    function _initScreenshots(totalWidth, totalHeight) {
        // 检查尺寸是否超过限制
        const badSize = (totalHeight > MAX_PRIMARY_DIMENSION ||
            totalWidth > MAX_PRIMARY_DIMENSION ||
            totalHeight * totalWidth > MAX_AREA);
        const biggerWidth = totalWidth > totalHeight;
        
        // 计算每个分块的最大尺寸
        const maxWidth = (!badSize ? totalWidth :
            (biggerWidth ? MAX_PRIMARY_DIMENSION : MAX_SECONDARY_DIMENSION));
        const maxHeight = (!badSize ? totalHeight :
            (biggerWidth ? MAX_SECONDARY_DIMENSION : MAX_PRIMARY_DIMENSION));
        
        // 计算分块数量
        const numCols = Math.ceil(totalWidth / maxWidth);
        const numRows = Math.ceil(totalHeight / maxHeight);
        
        // 创建结果数组
        const result = [];
        let canvasIndex = 0;

        // 创建所有需要的canvas
        for (let row = 0; row < numRows; row++) {
            for (let col = 0; col < numCols; col++) {
                const canvas = document.createElement('canvas');
                canvas.width = (col === numCols - 1 ? totalWidth % maxWidth || maxWidth : maxWidth);
                canvas.height = (row === numRows - 1 ? totalHeight % maxHeight || maxHeight : maxHeight);

                const left = col * maxWidth;
                const top = row * maxHeight;

                result.push({
                    canvas: canvas,
                    ctx: canvas.getContext('2d'),
                    index: canvasIndex,
                    left: left,
                    right: left + canvas.width,
                    top: top,
                    bottom: top + canvas.height
                });

                canvasIndex++;
            }
        }

        return result;
    }

    /**
     * 从截屏中筛选有效数据