自动调整TextView文本以适应边界
自动调整TextView文本以适应边界
我正在寻找一种最优方法来调整TextView
中包装文本的大小,使其适合其getHeight和getWidth边界内。我不仅仅要找到一种方法来换行文本-我也想确保它既换行又足够小,可以完全适合屏幕。
我在StackOverflow上看到过一些需要自动调整大小的情况,但它们要么是非常特殊的情况,有Hack的解决方案,要么没有解决方案,或者涉及递归重新绘制TextView
直到它足够小为止(这会消耗大量内存,并迫使用户观看每个递归步骤中的文本逐步缩小)。
但是我相信有人已经找到了一个好的解决方案,而不涉及我正在做的事情:编写几个解析和测量文本,调整文本大小并重复直到找到适当小的大小的重型例程。
tl; dr:是否有一种最佳实践方法来自动调整TextView
的大小,使其适合其getHeight和getWidth边界中的换行?
从2018年6月起,Android官方开始支持这个功能,适用于Android 4.0(API级别14)及以上版本。
请查看:可自动调整大小的TextView
从Android 8.0(API级别26)及更高版本开始:
编程方式:
setAutoSizeTextTypeUniformWithConfiguration(int autoSizeMinTextSize, int autoSizeMaxTextSize, int autoSizeStepGranularity, int unit) textView.setAutoSizeTextTypeUniformWithConfiguration( 1, 17, 1, TypedValue.COMPLEX_UNIT_DIP);
Android 8.0(API级别26)之前的版本:
编程方式:
TextViewCompat.setAutoSizeTextTypeUniformWithConfiguration( TextView textView, int autoSizeMinTextSize, int autoSizeMaxTextSize, int autoSizeStepGranularity, int unit) TextViewCompat.setAutoSizeTextTypeUniformWithConfiguration(textView, 1, 17, 1, TypedValue.COMPLEX_UNIT_DIP);
注意:TextView必须具有layout_width="match_parent"或绝对大小!
作为一名移动开发者,我很遗憾地发现没有任何本地支持自适应大小的内容。我的搜索没有找到适合我的解决方案,最终,我花费了大部分周末的时间,创建了自己的自适应文本视图。我将在这里发布代码,希望对其他人有帮助。
这个类使用原始文本视图的文本画笔和静态布局来测量高度。然后,我逐渐递减2个字体像素并重新测量,直到找到适合的大小为止。最后,如果文本仍然无法适配,我将附加省略号。我需要动画文本和重用视图的要求,在我看来,在我手头设备上这个方法运行得很快,也可以胜任这个任务。
/** * DO WHAT YOU WANT TO PUBLIC LICENSE * Version 2, December 2004 * * Copyright (C) 2004 Sam Hocevar* * Everyone is permitted to copy and distribute verbatim or modified * copies of this license document, and changing it is allowed as long * as the name is changed. * * DO WHAT YOU WANT TO PUBLIC LICENSE * TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION * * 0. You just DO WHAT YOU WANT TO. */ import android.content.Context; import android.text.Layout.Alignment; import android.text.StaticLayout; import android.text.TextPaint; import android.util.AttributeSet; import android.util.TypedValue; import android.widget.TextView; /** * Text view that auto adjusts text size to fit within the view. * If the text size equals the minimum text size and still does not * fit, append with an ellipsis. * * @author Chase Colburn * @since Apr 4, 2011 */ public class AutoResizeTextView extends TextView { // Minimum text size for this text view public static final float MIN_TEXT_SIZE = 20; // Interface for resize notifications public interface OnTextResizeListener { public void onTextResize(TextView textView, float oldSize, float newSize); } // Our ellipse string private static final String mEllipsis = "..."; // Registered resize listener private OnTextResizeListener mTextResizeListener; // Flag for text and/or size changes to force a resize private boolean mNeedsResize = false; // Text size that is set from code. This acts as a starting point for resizing private float mTextSize; // Temporary upper bounds on the starting text size private float mMaxTextSize = 0; // Lower bounds for text size private float mMinTextSize = MIN_TEXT_SIZE; // Text view line spacing multiplier private float mSpacingMult = 1.0f; // Text view additional line spacing private float mSpacingAdd = 0.0f; // Add ellipsis to text that overflows at the smallest text size private boolean mAddEllipsis = true; // Default constructor override public AutoResizeTextView(Context context) { this(context, null); } // Default constructor when inflating from XML file public AutoResizeTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } // Default constructor override public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mTextSize = getTextSize(); } /** * When text changes, set the force resize flag to true and reset the text size. */ @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { mNeedsResize = true; // Since this view may be reused, it is good to reset the text size resetTextSize(); } /** * If the text view size changed, set the force resize flag to true */ @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { if (w != oldw || h != oldh) { mNeedsResize = true; } } /** * Register listener to receive resize notifications * @param listener */ public void setOnResizeListener(OnTextResizeListener listener) { mTextResizeListener = listener; } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(float size) { super.setTextSize(size); mTextSize = getTextSize(); } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(int unit, float size) { super.setTextSize(unit, size); mTextSize = getTextSize(); } /** * Override the set line spacing to update our internal reference values */ @Override public void setLineSpacing(float add, float mult) { super.setLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } /** * Set the upper text size limit and invalidate the view * @param maxTextSize */ public void setMaxTextSize(float maxTextSize) { mMaxTextSize = maxTextSize; requestLayout(); invalidate(); } /** * Return upper text size limit * @return */ public float getMaxTextSize() { return mMaxTextSize; } /** * Set the lower text size limit and invalidate the view * @param minTextSize */ public void setMinTextSize(float minTextSize) { mMinTextSize = minTextSize; requestLayout(); invalidate(); } /** * Return lower text size limit * @return */ public float getMinTextSize() { return mMinTextSize; } /** * Set flag to add ellipsis to text that overflows at the smallest text size * @param addEllipsis */ public void setAddEllipsis(boolean addEllipsis) { mAddEllipsis = addEllipsis; } /** * Return flag to add ellipsis to text that overflows at the smallest text size * @return */ public boolean getAddEllipsis() { return mAddEllipsis; } /** * Reset the text to the original size */ public void resetTextSize() { if (mTextSize > 0) { super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize); mMaxTextSize = mTextSize; } } /** * Resize text after measuring */ @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if (changed || mNeedsResize) { int widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight(); int heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop(); resizeText(widthLimit, heightLimit); } super.onLayout(changed, left, top, right, bottom); } /** * Resize the text size with default width and height */ public void resizeText() { int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop(); int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight(); resizeText(widthLimit, heightLimit); } /** * Resize the text size with specified width and height * @param width * @param height */ public void resizeText(int width, int height) { CharSequence text = getText(); // Do not resize if the view does not have dimensions or there is no text if (text == null || text.length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) { return; } if (getTransformationMethod() != null) { text = getTransformationMethod().getTransformation(text, this); } // Get the text view's paint object TextPaint textPaint = getPaint(); // Store the current text size float oldTextSize = textPaint.getTextSize(); // If there is a max text size set, use the lesser of that and the default text size float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize; // Get the required text height int textHeight = getTextHeight(text, textPaint, width, targetTextSize); // Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes while (textHeight > height && targetTextSize > mMinTextSize) { targetTextSize = Math.max(targetTextSize - 2, mMinTextSize); textHeight = getTextHeight(text, textPaint, width, targetTextSize); } // If we had reached our minimum text size and still don't fit, append an ellipsis if (mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) { // Draw using a static layout // modified: use a copy of TextPaint for measuring TextPaint paint = new TextPaint(textPaint); // Draw using a static layout StaticLayout layout = new StaticLayout(text, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false); // Check that we have a least one line of rendered text if (layout.getLineCount() > 0) { // Since the line at the specific vertical position would be cut off, // we must trim up to the previous line int lastLine = layout.getLineForVertical(height) - 1; // If the text would not even fit on a single line, clear it if (lastLine < 0) { setText(""); } // Otherwise, trim to the previous line and add an ellipsis else { int start = layout.getLineStart(lastLine); int end = layout.getLineEnd(lastLine); float lineWidth = layout.getLineWidth(lastLine); float ellipseWidth = textPaint.measureText(mEllipsis); // Trim characters off until we have enough room to draw the ellipsis while (width < lineWidth + ellipseWidth) { lineWidth = textPaint.measureText(text.subSequence(start, --end + 1).toString()); } setText(text.subSequence(0, end) + mEllipsis); } } } // Some devices try to auto adjust line spacing, so force default line spacing // and invalidate the layout as a side effect setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize); setLineSpacing(mSpacingAdd, mSpacingMult); // Notify the listener if registered if (mTextResizeListener != null) { mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize); } // Reset force resize flag mNeedsResize = false; } // Set the text size of the text paint object and use a static layout to render text off screen before measuring private int getTextHeight(CharSequence source, TextPaint paint, int width, float textSize) { // modified: make a copy of the original TextPaint object for measuring // (apparently the object gets modified while measuring, see also the // docs for TextView.getPaint() (which states to access it read-only) TextPaint paintCopy = new TextPaint(paint); // Update the text paint object paintCopy.setTextSize(textSize); // Measure using a static layout StaticLayout layout = new StaticLayout(source, paintCopy, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); return layout.getHeight(); } }
警告。 有一个重要的已经修复的错误,影响了Android 3.1-4.04,导致所有AutoResizingTextView控件都不能工作。请阅读: https://stackoverflow.com/a/21851157/2075875