Android图文居中显示控件使用方法详解
最近项目中用到了文字图标的按钮,需要居中显示,如果用TextView实现的方式,必须同时设置padding和drawablePadding。如下:
<androidx.appcompat.widget.AppCompatTextView android:layout_width="200dp" android:layout_height="wrap_content" android:drawableLeft="@drawable/ic_xxx" android:drawablePadding="-60dp" android:minHeight="48dp" android:gravity="center" android:padding="80dp" />
这种方式需要自己做精确计算。比较麻烦。另外还有一种方式就是用线性布局包裹ImageView和TextView,但这样会增加布局层级。于是自己封装了一个控件DrawableCenterTextView。
attrs.xml文件中定义属性:
<declare-styleable name="DrawableCenterTextView"> <attr name="android:text" /> <attr name="android:textColor" /> <attr name="android:textSize" /> <attr name="android:textStyle" /> <attr name="android:drawablePadding" /> <attr name="android:drawableLeft" /> <attr name="android:drawableTop" /> <attr name="android:drawableRight" /> <attr name="android:drawableBottom" /> </declare-styleable>
对应的Java代码如下:
public class DrawableCenterTextView extends View { static final int LEFT = 0; static final int TOP = 1; static final int RIGHT = 2; static final int BOTTOM = 3; private CharSequence mText; private ColorStateList mTextColor; private float mTextSize; private int mTextStyle; private int mDrawablePadding; private Drawable[] mCompoundDrawables; private Rect mTextBounds; private Rect mDrawableLeftBounds; private Rect mDrawableTopBounds; private Rect mDrawableRightBounds; private Rect mDrawableBottomBounds; private TextPaint mTextPaint; public DrawableCenterTextView(Context context) { this(context, null); } public DrawableCenterTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public DrawableCenterTextView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); Drawable drawableLeft = null, drawableTop = null, drawableRight = null, drawableBottom = null; TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.DrawableCenterTextView, defStyleAttr, 0); mText = ta.getText(R.styleable.DrawableCenterTextView_android_text); mTextColor = ta.getColorStateList(R.styleable.DrawableCenterTextView_android_textColor); mTextSize = ta.getDimensionPixelSize(R.styleable.DrawableCenterTextView_android_textSize, 15); mTextStyle = ta.getInt(R.styleable.DrawableCenterTextView_android_textStyle, 0); drawableLeft = ta.getDrawable(R.styleable.DrawableCenterTextView_android_drawableLeft); drawableTop = ta.getDrawable(R.styleable.DrawableCenterTextView_android_drawableTop); drawableRight = ta.getDrawable(R.styleable.DrawableCenterTextView_android_drawableRight); drawableBottom = ta.getDrawable(R.styleable.DrawableCenterTextView_android_drawableBottom); mDrawablePadding = ta.getDimensionPixelSize(R.styleable.DrawableCenterTextView_android_drawablePadding, 0); ta.recycle(); if (mTextColor == null) { mTextColor = ColorStateList.valueOf(0xFF000000); } mTextPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG); mTextPaint.density = getResources().getDisplayMetrics().density; mTextPaint.setTextSize(mTextSize); setTypeface(Typeface.create(Typeface.DEFAULT, mTextStyle)); setCompoundDrawablesWithIntrinsicBounds(drawableLeft, drawableTop, drawableRight, drawableBottom); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int widthSize = MeasureSpec.getSize(widthMeasureSpec); int heightSize = MeasureSpec.getSize(heightMeasureSpec); int width; int height; //计算文本范围 calcTextBounds(); if (widthMode == MeasureSpec.EXACTLY) { width = widthSize; } else { width = mTextBounds.width(); if (mCompoundDrawables != null) { if (mCompoundDrawables[TOP] != null) { width = Math.max(width, mDrawableTopBounds.width()); } if (mCompoundDrawables[BOTTOM] != null) { width = Math.max(width, mDrawableBottomBounds.width()); } //加上左右内边距及drawable宽度和drawable间距 width += getCompoundPaddingLeft() + getCompoundPaddingRight(); width = Math.max(width, getSuggestedMinimumWidth()); if (widthMode == MeasureSpec.AT_MOST) { width = Math.min(widthSize, width); } } } if (heightMode == MeasureSpec.EXACTLY) { height = heightSize; } else { height = mTextBounds.height(); if (mCompoundDrawables != null) { if (mCompoundDrawables[LEFT] != null) { height = Math.max(height, mDrawableLeftBounds.height()); } if (mCompoundDrawables[RIGHT] != null) { height = Math.max(height, mDrawableRightBounds.height()); } //加上上下内边距及drawable高度和drawable间距 height += getCompoundPaddingTop() + getCompoundPaddingBottom(); height = Math.max(height, getSuggestedMinimumHeight()); if (heightMode == MeasureSpec.AT_MOST) { height = Math.min(heightSize, height); } } } setMeasuredDimension(width, height); } public int getCompoundPaddingTop() { if (mCompoundDrawables == null || mCompoundDrawables[TOP] == null) { return getPaddingTop(); } else { Rect rect = new Rect(); mCompoundDrawables[TOP].copyBounds(rect); return getPaddingTop() + mDrawablePadding + rect.height(); } } public int getCompoundPaddingBottom() { if (mCompoundDrawables == null || mCompoundDrawables[BOTTOM] == null) { return getPaddingBottom(); } else { Rect rect = new Rect(); mCompoundDrawables[BOTTOM].copyBounds(rect); return getPaddingBottom() + mDrawablePadding + rect.height(); } } public int getCompoundPaddingLeft() { if (mCompoundDrawables == null || mCompoundDrawables[LEFT] == null) { return getPaddingLeft(); } else { Rect rect = new Rect(); mCompoundDrawables[LEFT].copyBounds(rect); return getPaddingLeft() + mDrawablePadding + rect.width(); } } public int getCompoundPaddingRight() { if (mCompoundDrawables == null || mCompoundDrawables[RIGHT] == null) { return getPaddingRight(); } else { Rect rect = new Rect(); mCompoundDrawables[RIGHT].copyBounds(rect); return getPaddingRight() + mDrawablePadding + rect.width(); } } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); int vspace = getBottom() - getTop() - getCompoundPaddingBottom() - getCompoundPaddingTop(); //剩余垂直可绘制文本空间大小 int hspace = getRight() - getLeft() - getCompoundPaddingRight() - getCompoundPaddingLeft(); //剩余水平可绘制文本空间大小 if (mCompoundDrawables != null) { if (mCompoundDrawables[LEFT] != null) { canvas.save(); canvas.translate((hspace - mTextBounds.width()) / 2.0f + getPaddingLeft(), getCompoundPaddingTop() + (vspace - mDrawableLeftBounds.height()) / 2.0f); mCompoundDrawables[LEFT].draw(canvas); canvas.restore(); } if (mCompoundDrawables[RIGHT] != null) { canvas.save(); canvas.translate(getRight() - getLeft() - getPaddingRight() - (hspace - mTextBounds.width()) / 2.0f - mDrawableRightBounds.width(), getCompoundPaddingTop() + (vspace - mDrawableRightBounds.height()) / 2.0f); mCompoundDrawables[RIGHT].draw(canvas); canvas.restore(); } if (mCompoundDrawables[TOP] != null) { canvas.save(); canvas.translate(getCompoundPaddingLeft() + (hspace - mDrawableTopBounds.width()) / 2.0f, (vspace - mTextBounds.height()) / 2.0f + getPaddingTop()); mCompoundDrawables[TOP].draw(canvas); canvas.restore(); } if (mCompoundDrawables[BOTTOM] != null) { canvas.save(); canvas.translate(getCompoundPaddingLeft() + (hspace - mDrawableBottomBounds.width()) / 2.0f, getBottom() - getTop() - getPaddingBottom() - (vspace - mTextBounds.height()) / 2.0f - mDrawableBottomBounds.height()); mCompoundDrawables[BOTTOM].draw(canvas); canvas.restore(); } } if (!TextUtils.isEmpty(mText)) { float startX = (hspace - mTextBounds.width()) / 2.0f + getCompoundPaddingLeft(); //因为drawText以baseline为基准,因此需要向下移ascent float startY = (vspace - mTextBounds.height()) / 2.0f + getCompoundPaddingTop() - mTextPaint.getFontMetrics().ascent; mTextPaint.setColor(mTextColor.getColorForState(getDrawableState(), 0)); canvas.drawText(mText, 0, mText.length(), startX, startY, mTextPaint); } } @Override protected void drawableStateChanged() { super.drawableStateChanged(); if (mTextColor != null && mTextColor.isStateful()) { mTextPaint.setColor(mTextColor.getColorForState(getDrawableState(), 0)); } if (mCompoundDrawables != null) { final int[] state = getDrawableState(); for (Drawable dr : mCompoundDrawables) { if (dr != null && dr.isStateful() && dr.setState(state)) { invalidateDrawable(dr); } } } } public void setCompoundDrawablesWithIntrinsicBounds(@Nullable Drawable left, @Nullable Drawable top, @Nullable Drawable right, @Nullable Drawable bottom) { if (left != null) { left.setBounds(0, 0, left.getIntrinsicWidth(), left.getIntrinsicHeight()); } if (right != null) { right.setBounds(0, 0, right.getIntrinsicWidth(), right.getIntrinsicHeight()); } if (top != null) { top.setBounds(0, 0, top.getIntrinsicWidth(), top.getIntrinsicHeight()); } if (bottom != null) { bottom.setBounds(0, 0, bottom.getIntrinsicWidth(), bottom.getIntrinsicHeight()); } setCompoundDrawables(left, top, right, bottom); } public void setCompoundDrawables(@Nullable Drawable left, @Nullable Drawable top, @Nullable Drawable right, @Nullable Drawable bottom) { if (mCompoundDrawables == null) { mCompoundDrawables = new Drawable[4]; } else { if (mCompoundDrawables[LEFT] != null && mCompoundDrawables[LEFT] != left) { mCompoundDrawables[LEFT].setCallback(null); } if (mCompoundDrawables[TOP] != null && mCompoundDrawables[TOP] != top) { mCompoundDrawables[TOP].setCallback(null); } if (mCompoundDrawables[RIGHT] != null && mCompoundDrawables[RIGHT] != right) { mCompoundDrawables[RIGHT].setCallback(null); } if (mCompoundDrawables[BOTTOM] != null && mCompoundDrawables[BOTTOM] != bottom) { mCompoundDrawables[BOTTOM].setCallback(null); } } if (left != null) { mDrawableLeftBounds = new Rect(); left.copyBounds(mDrawableLeftBounds); left.setCallback(this); mCompoundDrawables[LEFT] = left; } else { mCompoundDrawables[LEFT] = null; } if (top != null) { mDrawableTopBounds = new Rect(); top.copyBounds(mDrawableTopBounds); top.setCallback(this); mCompoundDrawables[TOP] = top; } else { mCompoundDrawables[TOP] = null; } if (right != null) { mDrawableRightBounds = new Rect(); right.copyBounds(mDrawableRightBounds); right.setCallback(this); mCompoundDrawables[RIGHT] = right; } else { mCompoundDrawables[RIGHT] = null; } if (bottom != null) { mDrawableBottomBounds = new Rect(); bottom.copyBounds(mDrawableBottomBounds); bottom.setCallback(this); mCompoundDrawables[BOTTOM] = bottom; } else { mCompoundDrawables[BOTTOM] = null; } invalidate(); requestLayout(); } public void setText(CharSequence text) { this.mText = text; invalidate(); requestLayout(); } public void setTextSize(float textSize) { this.mTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, textSize, getResources().getDisplayMetrics()); invalidate(); requestLayout(); } public void setTextColor(@ColorInt int textColor) { this.mTextColor = ColorStateList.valueOf(textColor); invalidate(); } public void setTypeface(@Nullable Typeface tf) { if (mTextPaint.getTypeface() != tf) { mTextPaint.setTypeface(tf); requestLayout(); invalidate(); } } private void calcTextBounds() { mTextBounds = new Rect(); if (TextUtils.isEmpty(mText)) return; if (Build.VERSION.SDK_INT > Build.VERSION_CODES.Q) { mTextPaint.getTextBounds(mText, 0, mText.length(), mTextBounds); } else { int width = (int) Math.ceil(mTextPaint.measureText(mText.toString())); Paint.FontMetrics fontMetrics = mTextPaint.getFontMetrics(); int height = (int) Math.ceil(fontMetrics.descent - fontMetrics.ascent); mTextBounds.set(0, 0, width, height); } } }
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