#target photoshop

/*
    Uniformly resize the current canvas area.
    Scale range: 0.1 to 5
    Default scale: 2

    Layer contents are not scaled. The canvas expands or crops
    equally from its center according to the entered scale.
*/

(function () {
    function showMessage(text) {
        alert(text);
    }

    if (app.documents.length === 0) {
        showMessage("请先打开一个文档。");
        return;
    }

    var document = app.activeDocument;
    var currentWidth = Math.round(document.width.as("px"));
    var currentHeight = Math.round(document.height.as("px"));

    var dialog = new Window("dialog", "修改画布大小");
    dialog.orientation = "column";
    dialog.alignChildren = "fill";

    // Method 1: uniformly resize with a scale slider and numeric input.
    var scalePanel = dialog.add("panel", undefined, "方式一：等比例缩放");
    scalePanel.orientation = "column";
    scalePanel.alignChildren = "fill";

    var scaleMode = scalePanel.add("radiobutton", undefined, "使用缩放倍率");
    scaleMode.value = true;

    var scaleGroup = scalePanel.add("group");
    scaleGroup.orientation = "row";

    var scaleSlider = scaleGroup.add("slider", undefined, 2, 0.1, 5);
    scaleSlider.preferredSize.width = 220;

    var scaleInput = scaleGroup.add("edittext", undefined, "2");
    scaleInput.characters = 6;

    scaleGroup.add("statictext", undefined, "倍（0.1 - 5）");

    // Method 2: enter the target canvas width and height independently.
    var sizePanel = dialog.add("panel", undefined, "方式二：指定宽高");
    sizePanel.orientation = "column";
    sizePanel.alignChildren = "left";

    var sizeMode = sizePanel.add("radiobutton", undefined, "使用指定宽度和高度");

    var widthGroup = sizePanel.add("group");
    widthGroup.orientation = "row";
    widthGroup.add("statictext", undefined, "宽度：");
    var widthInput = widthGroup.add("edittext", undefined, String(currentWidth));
    widthInput.characters = 10;
    widthGroup.add("statictext", undefined, "px");

    var heightGroup = sizePanel.add("group");
    heightGroup.orientation = "row";
    heightGroup.add("statictext", undefined, "高度：");
    var heightInput = heightGroup.add("edittext", undefined, String(currentHeight));
    heightInput.characters = 10;
    heightGroup.add("statictext", undefined, "px");

    var buttonGroup = dialog.add("group");
    buttonGroup.alignment = "right";
    var cancelButton = buttonGroup.add("button", undefined, "取消", { name: "cancel" });
    var okButton = buttonGroup.add("button", undefined, "确定", { name: "ok" });

    var resultWidth = null;
    var resultHeight = null;

    function parseNumber(text) {
        return parseFloat(text.replace(",", "."));
    }

    function formatScale(value) {
        return String(Math.round(value * 100) / 100);
    }

    function updateControlState() {
        scaleSlider.enabled = scaleMode.value;
        scaleInput.enabled = scaleMode.value;
        widthInput.enabled = sizeMode.value;
        heightInput.enabled = sizeMode.value;
    }

    scaleMode.onClick = function () {
        scaleMode.value = true;
        sizeMode.value = false;
        updateControlState();
    };

    sizeMode.onClick = function () {
        sizeMode.value = true;
        scaleMode.value = false;
        updateControlState();
    };

    scaleSlider.onChanging = function () {
        scaleInput.text = formatScale(scaleSlider.value);
    };

    scaleInput.onChange = function () {
        var value = parseNumber(scaleInput.text);
        if (!isNaN(value) && value >= 0.1 && value <= 5) {
            scaleSlider.value = value;
            scaleInput.text = formatScale(value);
        }
    };

    okButton.onClick = function () {
        if (scaleMode.value) {
            var scaleValue = parseNumber(scaleInput.text);

            if (isNaN(scaleValue) || scaleValue < 0.1 || scaleValue > 5) {
                showMessage("请输入 0.1 到 5 之间的缩放倍率。");
                scaleInput.active = true;
                return;
            }

            resultWidth = Math.max(1, Math.round(currentWidth * scaleValue));
            resultHeight = Math.max(1, Math.round(currentHeight * scaleValue));
        } else {
            var widthValue = parseNumber(widthInput.text);
            var heightValue = parseNumber(heightInput.text);

            if (isNaN(widthValue) || widthValue <= 0) {
                showMessage("请输入有效的画布宽度。");
                widthInput.active = true;
                return;
            }

            if (isNaN(heightValue) || heightValue <= 0) {
                showMessage("请输入有效的画布高度。");
                heightInput.active = true;
                return;
            }

            resultWidth = Math.round(widthValue);
            resultHeight = Math.round(heightValue);
        }

        dialog.close(1);
    };

    cancelButton.onClick = function () {
        dialog.close(0);
    };

    updateControlState();

    if (dialog.show() !== 1 || resultWidth === null || resultHeight === null) {
        return;
    }

    try {
        document.resizeCanvas(
            new UnitValue(resultWidth, "px"),
            new UnitValue(resultHeight, "px"),
            AnchorPosition.MIDDLECENTER
        );
    } catch (error) {
        showMessage("修改画布失败：\n" + error.message);
    }
}());