StaticLayout如何在Android中使用？

我需要构建自己的自定义,TextView所以我一直在学习StaticLayout在画布上绘制文本.这比Canvas.drawText()直接使用更好,或者说文档说的.但是,文档没有给出任何示例.只有模糊的参考才能StaticLayout.Builder成为更新的方法.

我在这里找到了一个例子,但似乎有点过时了.

我终于工作了,但是我在下面添加了我的解释.

StaticLayout(类似于DynamicLayout和BoringLayout)用于在画布上布局和绘制文本.它通常用于以下任务:

测量布局后多行文字的大小.

在位图图像上绘制文本.

创建一个处理自己的文本布局的自定义视图(而不是使用嵌入式创建复合视图TextView).TextView本身使用StaticLayout 内部.

测量文字大小

单线

如果您只有一行文字,可以用Paint或测量它TextPaint.

String text = "This is some text."

TextPaint myTextPaint = new TextPaint();
mTextPaint.setAntiAlias(true);
mTextPaint.setTextSize(16 * getResources().getDisplayMetrics().density);
mTextPaint.setColor(0xFF000000);

float width = mTextPaint.measureText(text);
float height = -mTextPaint.ascent() + mTextPaint.descent();

多行

但是,如果有换行并且你需要高度,那么最好使用a StaticLayout.你提供宽度,然后你可以从中获得高度StaticLayout.

String text = "This is some text. This is some text. This is some text. This is some text. This is some text. This is some text.";

TextPaint myTextPaint = new TextPaint();
myTextPaint.setAntiAlias(true);
myTextPaint.setTextSize(16 * getResources().getDisplayMetrics().density);
myTextPaint.setColor(0xFF000000);

int width = 200;
Layout.Alignment alignment = Layout.Alignment.ALIGN_NORMAL;
float spacingMultiplier = 1;
float spacingAddition = 0;
boolean includePadding = false;

StaticLayout myStaticLayout = new StaticLayout(text, myTextPaint, width, alignment, spacingMultiplier, spacingAddition, includePadding);

float height = myStaticLayout.getHeight(); 

新API

如果您想使用较新的StaticLayout.Builder(可从API 23获得),您可以获得如下布局:

StaticLayout.Builder builder = StaticLayout.Builder.obtain(text, 0, text.length(), myTextPaint, width);
StaticLayout myStaticLayout = builder.build();

您可以使用点表示法来添加额外设置:

StaticLayout.Builder builder = StaticLayout.Builder.obtain(text, 0, text.length(), myTextPaint, width)
        .setAlignment(Layout.Alignment.ALIGN_NORMAL)
        .setLineSpacing(spacingMultiplier, spacingAddition)
        .setIncludePad(includePadding)
        .setMaxLines(5);
StaticLayout myStaticLayout = builder.build();

我可能会在将来扩展它,但是现在看一下这个帖子的一个使用StaticLayout和返回位图的方法的例子.

以下是使用a的自定义视图的示例StaticLayout.它表现得像一个简单的TextView.当文本太长而无法放在屏幕上时,它会自动换行并增加其高度.

码

MyView.java

public class MyView extends View {

    String mText = "This is some text.";
    TextPaint mTextPaint;
    StaticLayout mStaticLayout;

    // use this constructor if creating MyView programmatically
    public MyView(Context context) {
        super(context);
        initLabelView();
    }

    // this constructor is used when created from xml
    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initLabelView();
    }

    private void initLabelView() {
        mTextPaint = new TextPaint();
        mTextPaint.setAntiAlias(true);
        mTextPaint.setTextSize(16 * getResources().getDisplayMetrics().density);
        mTextPaint.setColor(0xFF000000);

        // default to a single line of text
        int width = (int) mTextPaint.measureText(mText);
        mStaticLayout = new StaticLayout(mText, mTextPaint, (int) width, Layout.Alignment.ALIGN_NORMAL, 1.0f, 0, false);

        // New API alternate
        //
        // StaticLayout.Builder builder = StaticLayout.Builder.obtain(mText, 0, mText.length(), mTextPaint, width)
        //        .setAlignment(Layout.Alignment.ALIGN_NORMAL)
        //        .setLineSpacing(1, 0) // multiplier, add
        //        .setIncludePad(false);
        // mStaticLayout = builder.build();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // Tell the parent layout how big this view would like to be
        // but still respect any requirements (measure specs) that are passed down.

        // determine the width
        int width;
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthRequirement = MeasureSpec.getSize(widthMeasureSpec);
        if (widthMode == MeasureSpec.EXACTLY) {
            width = widthRequirement;
        } else {
            width = mStaticLayout.getWidth() + getPaddingLeft() + getPaddingRight();
            if (widthMode == MeasureSpec.AT_MOST) {
                if (width > widthRequirement) {
                    width = widthRequirement;
                    // too long for a single line so relayout as multiline
                    mStaticLayout = new StaticLayout(mText, mTextPaint, width, Layout.Alignment.ALIGN_NORMAL, 1.0f, 0, false);
                }
            }
        }

        // determine the height
        int height;
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightRequirement = MeasureSpec.getSize(heightMeasureSpec);
        if (heightMode == MeasureSpec.EXACTLY) {
            height = heightRequirement;
        } else {
            height = mStaticLayout.getHeight() + getPaddingTop() + getPaddingBottom();
            if (heightMode == MeasureSpec.AT_MOST) {
                height = Math.min(height, heightRequirement);
            }
        }

        // Required call: set width and height
        setMeasuredDimension(width, height);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // do as little as possible inside onDraw to improve performance

        // draw the text on the canvas after adjusting for padding
        canvas.save();
        canvas.translate(getPaddingLeft(), getPaddingTop());
        mStaticLayout.draw(canvas);
        canvas.restore();
    }
}

activity_main.xml中

笔记

这个,这个,这对于学习如何创建自定义文本处理视图很有用.

如果要添加可以从代码或xml设置的自定义属性,请参阅创建视图类.