Android中带渐变的文本

TextView secondTextView = new TextView(this);
Shader textShader=new LinearGradient(0, 0, 0, 20,
            new int[]{Color.GREEN,Color.BLUE},
            new float[]{0, 1}, TileMode.CLAMP);
secondTextView.getPaint().setShader(textShader);

似乎不可能扩展textView以使用渐变绘制文本。但是,可以通过创建画布并在其上绘制来实现此效果。首先我们需要 declare our custom UI element . 在初始阶段,我们需要创建 Layout . 在这种情况下,我们将使用 BoringLayout 它只支持单行文本。

Shader textShader=new LinearGradient(0, 0, 0, 20,
    new int[]{bottom,top},
    new float[]{0, 1}, TileMode.CLAMP);//Assumes bottom and top are colors defined above
textPaint.setTextSize(textSize);
textPaint.setShader(textShader);
BoringLayout.Metrics boringMetrics=BoringLayout.isBoring(text, textPaint);
boringLayout=new BoringLayout(text, textPaint, 0, Layout.Alignment.ALIGN_CENTER,
            0.0f, 0.0f, boringMetrics, false);

然后我们重写 onMeasure 和 onDraw :

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
    setMeasuredDimension((int) textPaint.measureText(text), (int) textPaint.getFontSpacing());
}

@Override
protected void onDraw(Canvas canvas){
    super.onDraw(canvas);
    boringLayout.draw(canvas);
}

我们的实施 OnDRAW 此时相当懒惰(它完全忽略了测量规格!但是只要你保证视图有足够的空间,它就可以正常工作。

或者,可以从 Canvas 并覆盖 onPaint 方法。如果这样做,那么不幸的是,正在绘制的文本的锚定将始终位于底部,因此我们必须添加 -textPaint.getFontMetricsInt().ascent() 到我们的Y坐标。

我已经建立了一个包含这两种方法的库。您可以在XML中创建GradientTextView,或者只使用GradientTextView.setGradient(textView textView…)在常规的textView对象上进行创建。

https://github.com/koush/Widgets

在这里,多行支持作为一个线性。这也适用于按钮。

textView.getPaint().setShader(new LinearGradient(0,0,0,textView.getLineHeight(), startColor, endColor, Shader.TileMode.REPEAT));

我用了5种颜色的最上面的答案(@taras),但是有一个问题:textview看起来像是我在上面加了一个白色的盖子。这是我的代码和截图。

        textView = (TextView) findViewById(R.id.main_tv);
        textView.setText("Tianjin, China".toUpperCase());

        TextPaint paint = textView.getPaint();
        float width = paint.measureText("Tianjin, China");

        Shader textShader = new LinearGradient(0, 0, width, textView.getTextSize(),
                new int[]{
                        Color.parseColor("#F97C3C"),
                        Color.parseColor("#FDB54E"),
                        Color.parseColor("#64B678"),
                        Color.parseColor("#478AEA"),
                        Color.parseColor("#8446CC"),
                }, null, Shader.TileMode.CLAMP);
        textView.getPaint().setShader(textShader);

几个小时后,我发现我需要打电话 textView.setTextColor() 第一种颜色的渐变。然后屏幕截图:

希望能帮助别人!

一个简单但有点局限的解决方案是使用这些属性:

android:fadingEdge="horizontal"
android:scrollHorizontally="true"

我在文本字段中使用它,如果文本字段太长,我希望它们淡出。

这是一个很好的方法:

/**
 * sets a vertical gradient on the textView's paint, so that on its onDraw method, it will use it.
 *
 * @param viewAlreadyHasSize
 *            set to true only if the textView already has a size
 */
public static void setVerticalGradientOnTextView(final TextView tv, final int positionsAndColorsResId,
        final boolean viewAlreadyHasSize) {
    final String[] positionsAndColors = tv.getContext().getResources().getStringArray(positionsAndColorsResId);
    final int[] colors = new int[positionsAndColors.length];
    float[] positions = new float[positionsAndColors.length];
    for (int i = 0; i < positionsAndColors.length; ++i) {
        final String positionAndColors = positionsAndColors[i];
        final int delimeterPos = positionAndColors.lastIndexOf(':');
        if (delimeterPos == -1 || positions == null) {
            positions = null;
            colors[i] = Color.parseColor(positionAndColors);
        } else {
            positions[i] = Float.parseFloat(positionAndColors.substring(0, delimeterPos));
            String colorStr = positionAndColors.substring(delimeterPos + 1);
            if (colorStr.startsWith("0x"))
                colorStr = '#' + colorStr.substring(2);
            else if (!colorStr.startsWith("#"))
                colorStr = '#' + colorStr;
            colors[i] = Color.parseColor(colorStr);
        }
    }
    setVerticalGradientOnTextView(tv, colors, positions, viewAlreadyHasSize);
}

/**
 * sets a vertical gradient on the textView's paint, so that on its onDraw method, it will use it. <br/>
 *
 * @param colors
 *            the colors to use. at least one should exist.
 * @param tv
 *            the textView to set the gradient on it
 * @param positions
 *            where to put each color (fraction, max is 1). if null, colors are spread evenly .
 * @param viewAlreadyHasSize
 *            set to true only if the textView already has a size
 */
public static void setVerticalGradientOnTextView(final TextView tv, final int[] colors, final float[] positions,
        final boolean viewAlreadyHasSize) {
    final Runnable runnable = new Runnable() {

        @Override
        public void run() {
            final TileMode tile_mode = TileMode.CLAMP;
            final int height = tv.getHeight();
            final LinearGradient lin_grad = new LinearGradient(0, 0, 0, height, colors, positions, tile_mode);
            final Shader shader_gradient = lin_grad;
            tv.getPaint().setShader(shader_gradient);
        }
    };
    if (viewAlreadyHasSize)
        runnable.run();
    else
        runJustBeforeBeingDrawn(tv, runnable);
}

public static void runJustBeforeBeingDrawn(final View view, final Runnable runnable) {
    final OnPreDrawListener preDrawListener = new OnPreDrawListener() {
        @Override
        public boolean onPreDraw() {
            view.getViewTreeObserver().removeOnPreDrawListener(this);
            runnable.run();
            return true;
        }
    };
    view.getViewTreeObserver().addOnPreDrawListener(preDrawListener);
}

另外,如果您希望使用渐变位图,而不是实际的,请使用:

/**
 * sets an image for the textView <br/>
 * NOTE: this function must be called after you have the view have its height figured out <br/>
 */
public static void setBitmapOnTextView(final TextView tv, final Bitmap bitmap) {
    final TileMode tile_mode = TileMode.CLAMP;
    final int height = tv.getHeight();
    final int width = tv.getWidth();
    final Bitmap temp = Bitmap.createScaledBitmap(bitmap, width, height, true);
    final BitmapShader bitmapShader = new BitmapShader(temp, tile_mode, tile_mode);
    tv.getPaint().setShader(bitmapShader);
}

编辑:在绘制之前替代runjustbeforebeingdrawn: https://stackoverflow.com/a/28136027/878126

下面是LinearLayout的一个示例,您也可以将这个示例用于textView,并且在源代码中不会有渐变编码,您可以获取源代码并从该站点本身添加代码。- http://android-codes-examples.blogspot.com/2011/07/design-linearlayout-or-textview-and-any.html