Android 自繪TextView解決提前換行問題，支援圖文混排
阿新 • • 發佈：2018-12-23
先看下效果圖：
上面是MTextView，下面是預設的TextView。
一、原因
用最簡單的全英文句子為例，如果有一個很長的單詞，這一行剩餘的空間顯示不下了，那麼規則就是不打斷單詞，而是把整個單詞丟到下一行開始顯示。這樣本來沒有錯。一是咱們中國人都是方塊字，怎麼都放得下，不存在英文的這個問題。所以不習慣那個排版。二是如果TextView裡面有圖片，如圖，
二、解決方法
最簡單的就是表情之間加空格，如果不想這麼做，就只有自己來畫啦。
先給初學的朋友解釋一下View繪製的流程，首先是onMeasure(int widthMeasureSpec, int heightMeasureSpec),onMeasure執行的時候，就是父View在問你，小朋友，你要佔多大的地兒呀？當然，問你的時候，會給你個限制條件，就是那兩引數，以widthMeasureSpec為例，這引數不能直接用，得先拆開，用int widthMode = MeasureSpec.getMode(widthMeasureSpec) 和 int widthSize = MeasureSpec.getSize(widthMeasureSpec);widthMode就三種情況：
MeasureSpec.EXACTLY：你就widthSize那麼寬就行了。
MeasureSpec.AT_MOST：你最多隻能widthSize那麼寬。
MeasureSpec.UNSPECIFIED：未指定，你愛多寬多寬。
當然，其實這隻父View給你的建議，遵不遵守你自己看著辦，但是自己亂來導致顯示不全就不是父View的錯了。
最終你聽取了建議，思量了一番，覺得自己應該有width那麼寬，height那麼高，最後就得用setMeasuredDimension(width, height)這個函式真正確定自己的高寬。然後onMeasure()的工作就完了。
然後就是onDraw(Canvas canvas)，這個就簡單了，canvas就是父View給的一塊畫布，愛在上面畫啥都行，比如寫個字drawText( String text,float
x, float y, Paint paint)，
text是要寫的字，paint是寫字的筆，值得注意的是x,y座標是相對於你自己這一小塊畫布的左上角的。最左上就是0,0右下是width,height
上程式碼
</pre><pre>/**
* @author huangwei
* @version SocialClient 1.2.0
* @功能 圖文混排TextView，請使用{@link #setMText(CharSequence)}
* @2014年5月27日
* @下午5:29:27
*/
public class MTextView extends TextView
{
/**
* 快取測量過的資料
*/
private static HashMap<String, SoftReference<MeasuredData>> measuredData = new HashMap<String, SoftReference<MeasuredData>>();
private static int hashIndex = 0;
/**
* 儲存當前文字內容，每個item為一行
*/
ArrayList<LINE> contentList = new ArrayList<LINE>();
private Context context;
/**
* 用於測量字元寬度
*/
private TextPaint paint = new TextPaint();
// private float lineSpacingMult = 0.5f;
private int textColor = Color.BLACK;
//行距
private float lineSpacing;
private int lineSpacingDP = 5;
/**
* 最大寬度
*/
private int maxWidth;
/**
* 只有一行時的寬度
*/
private int oneLineWidth = -1;
/**
* 已繪的行中最寬的一行的寬度
*/
private float lineWidthMax = -1;
/**
* 儲存當前文字內容,每個item為一個字元或者一個SpanObject
*/
private ArrayList<Object> obList = new ArrayList<Object>();
/**
* 是否使用預設{@link #onMeasure(int, int)}和{@link #onDraw(Canvas)}
*/
private boolean useDefault = false;
private CharSequence text = "";
private int minHeight;
/**
* 用以獲取螢幕高寬
*/
private DisplayMetrics displayMetrics;
/**
* {@link android.text.style.BackgroundColorSpan}用
*/
private Paint textBgColorPaint = new Paint();
/**
* {@link android.text.style.BackgroundColorSpan}用
*/
private Rect textBgColorRect = new Rect();
public MTextView(Context context)
{
super(context);
this.context = context;
paint.setAntiAlias(true);
lineSpacing = dip2px(context, lineSpacingDP);
minHeight = dip2px(context, 30);
displayMetrics = new DisplayMetrics();
}
public MTextView(Context context,AttributeSet attrs)
{
super(context,attrs);
this.context = context;
paint.setAntiAlias(true);
lineSpacing = dip2px(context, lineSpacingDP);
minHeight = dip2px(context, 30);
displayMetrics = new DisplayMetrics();
}
public static int px2sp(Context context, float pxValue)
{
final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
return (int) (pxValue / fontScale + 0.5f);
}
/**
* 根據手機的解析度從 dp 的單位 轉成為 px(畫素)
*/
public static int dip2px(Context context, float dpValue)
{
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}
@Override
public void setMaxWidth(int maxpixels)
{
super.setMaxWidth(maxpixels);
maxWidth = maxpixels;
}
@Override
public void setMinHeight(int minHeight)
{
super.setMinHeight(minHeight);
this.minHeight = minHeight;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
if (useDefault)
{
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
return;
}
int width = 0, height = 0;
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
switch (widthMode)
{
case MeasureSpec.EXACTLY:
width = widthSize;
break;
case MeasureSpec.AT_MOST:
width = widthSize;
break;
case MeasureSpec.UNSPECIFIED:
((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
width = displayMetrics.widthPixels;
break;
default:
break;
}
if (maxWidth > 0)
width = Math.min(width, maxWidth);
paint.setTextSize(this.getTextSize());
paint.setColor(textColor);
int realHeight = measureContentHeight((int) width);
//如果實際行寬少於預定的寬度，減少行寬以使其內容橫向居中
int leftPadding = getCompoundPaddingLeft();
int rightPadding = getCompoundPaddingRight();
width = Math.min(width, (int) lineWidthMax + leftPadding + rightPadding);
if (oneLineWidth > -1)
{
width = oneLineWidth;
}
switch (heightMode)
{
case MeasureSpec.EXACTLY:
height = heightSize;
break;
case MeasureSpec.AT_MOST:
height = realHeight;
break;
case MeasureSpec.UNSPECIFIED:
height = realHeight;
break;
default:
break;
}
height += getCompoundPaddingTop() + getCompoundPaddingBottom();
height = Math.max(height, minHeight);
setMeasuredDimension(width, height);
}
@Override
protected void onDraw(Canvas canvas)
{
if (useDefault)
{
super.onDraw(canvas);
return;
}
if (contentList.isEmpty())
return;
int width;
Object ob;
int leftPadding = getCompoundPaddingLeft();
int topPadding = getCompoundPaddingTop();
float height = 0 + topPadding + lineSpacing;
//只有一行時
if (oneLineWidth != -1)
{
height = getMeasuredHeight() / 2 - contentList.get(0).height / 2;
}
for (LINE aContentList : contentList)
{
//繪製一行
float realDrawedWidth = leftPadding;
for (int j = 0; j < aContentList.line.size(); j++)
{
ob = aContentList.line.get(j);
width = aContentList.widthList.get(j);
if (ob instanceof String)
{
canvas.drawText((String) ob, realDrawedWidth, height + aContentList.height - paint.getFontMetrics().descent, paint);
realDrawedWidth += width;
}
else if (ob instanceof SpanObject)
{
Object span = ((SpanObject) ob).span;
if(span instanceof ImageSpan)
{
ImageSpan is = (ImageSpan) span;
Drawable d = is.getDrawable();
int left = (int) (realDrawedWidth);
int top = (int) height;
int right = (int) (realDrawedWidth + width);
int bottom = (int) (height + aContentList.height);
d.setBounds(left, top, right, bottom);
d.draw(canvas);
realDrawedWidth += width;
}
else if(span instanceof BackgroundColorSpan)
{
textBgColorPaint.setColor(((BackgroundColorSpan) span).getBackgroundColor());
textBgColorPaint.setStyle(Style.FILL);
textBgColorRect.left = (int) realDrawedWidth;
int textHeight = (int) getTextSize();
textBgColorRect.top = (int) (height + aContentList.height - textHeight - paint.getFontMetrics().descent);
textBgColorRect.right = textBgColorRect.left+width;
textBgColorRect.bottom = (int) (height + aContentList.height + lineSpacing - paint.getFontMetrics().descent);
canvas.drawRect(textBgColorRect, textBgColorPaint);
canvas.drawText(((SpanObject) ob).source.toString(), realDrawedWidth, height + aContentList.height - paint.getFontMetrics().descent, paint);
realDrawedWidth += width;
}
else//做字串處理
{
canvas.drawText(((SpanObject) ob).source.toString(), realDrawedWidth, height + aContentList.height - paint.getFontMetrics().descent, paint);
realDrawedWidth += width;
}
}
}
height += aContentList.height + lineSpacing;
}
}
@Override
public void setTextColor(int color)
{
super.setTextColor(color);
textColor = color;
}
/**
* 用於帶ImageSpan的文字內容所佔高度測量
* @param width 預定的寬度
* @return 所需的高度
*/
private int measureContentHeight(int width)
{
int cachedHeight = getCachedData(text.toString(), width);
if (cachedHeight > 0)
{
return cachedHeight;
}
// 已繪的寬度
float obWidth = 0;
float obHeight = 0;
float textSize = this.getTextSize();
FontMetrics fontMetrics = paint.getFontMetrics();
//行高
float lineHeight = fontMetrics.bottom - fontMetrics.top;
//計算出的所需高度
float height = lineSpacing;
int leftPadding = getCompoundPaddingLeft();
int rightPadding = getCompoundPaddingRight();
float drawedWidth = 0;
boolean splitFlag = false;//BackgroundColorSpan拆分用
width = width - leftPadding - rightPadding;
oneLineWidth = -1;
contentList.clear();
StringBuilder sb;
LINE line = new LINE();
for (int i = 0; i < obList.size(); i++)
{
Object ob = obList.get(i);
if (ob instanceof String)
{
obWidth = paint.measureText((String) ob);
obHeight = textSize;
}
else if (ob instanceof SpanObject)
{
Object span = ((SpanObject) ob).span;
if(span instanceof ImageSpan)
{
Rect r = ((ImageSpan)span).getDrawable().getBounds();
obWidth = r.right - r.left;
obHeight = r.bottom - r.top;
if (obHeight > lineHeight)
lineHeight = obHeight;
}
else if(span instanceof BackgroundColorSpan)
{
String str = ((SpanObject) ob).source.toString();
obWidth = paint.measureText(str);
obHeight = textSize;
//如果太長,拆分
int k= str.length()-1;
while(width - drawedWidth < obWidth)
{
obWidth = paint.measureText(str.substring(0,k--));
}
if(k < str.length()-1)
{
splitFlag = true;
SpanObject so1 = new SpanObject();
so1.start = ((SpanObject) ob).start;
so1.end = so1.start + k;
so1.source = str.substring(0,k+1);
so1.span = ((SpanObject) ob).span;
SpanObject so2 = new SpanObject();
so2.start = so1.end;
so2.end = ((SpanObject) ob).end;
so2.source = str.substring(k+1,str.length());
so2.span = ((SpanObject) ob).span;
ob = so1;
obList.set(i,so2);
i--;
}
}//做字串處理
else
{
String str = ((SpanObject) ob).source.toString();
obWidth = paint.measureText(str);
obHeight = textSize;
}
}
//這一行滿了，存入contentList,新起一行
if (width - drawedWidth < obWidth || splitFlag)
{
splitFlag = false;
contentList.add(line);
if (drawedWidth > lineWidthMax)
{
lineWidthMax = drawedWidth;
}
drawedWidth = 0;
height += line.height + lineSpacing;
lineHeight = obHeight;
line = new LINE();
}
drawedWidth += obWidth;
if (ob instanceof String && line.line.size() > 0 && (line.line.get(line.line.size() - 1) instanceof String))
{
int size = line.line.size();
sb = new StringBuilder();
sb.append(line.line.get(size - 1));
sb.append(ob);
ob = sb.toString();
obWidth = obWidth + line.widthList.get(size - 1);
line.line.set(size - 1, ob);
line.widthList.set(size - 1, (int) obWidth);
line.height = (int) lineHeight;
}
else
{
line.line.add(ob);
line.widthList.add((int) obWidth);
line.height = (int) lineHeight;
}
}
if (drawedWidth > lineWidthMax)
{
lineWidthMax = drawedWidth;
}
if (line != null && line.line.size() > 0)
{
contentList.add(line);
height += lineHeight + lineSpacing;
}
if (contentList.size() <= 1)
{
oneLineWidth = (int) drawedWidth + leftPadding + rightPadding;
height = lineSpacing + lineHeight + lineSpacing;
}
cacheData(width, (int) height);
return (int) height;
}
/**
* 獲取快取的測量資料，避免多次重複測量
* @param text
* @param width
* @return height
*/
@SuppressWarnings("unchecked")
private int getCachedData(String text, int width)
{
SoftReference<MeasuredData> cache = measuredData.get(text);
if (cache == null)
return -1;
MeasuredData md = cache.get();
if (md != null && md.textSize == this.getTextSize() && width == md.width)
{
lineWidthMax = md.lineWidthMax;
contentList = (ArrayList<LINE>) md.contentList.clone();
oneLineWidth = md.oneLineWidth;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < contentList.size(); i++)
{
LINE line = contentList.get(i);
sb.append(line.toString());
}
return md.measuredHeight;
}
else
return -1;
}
/**
* 快取已測量的資料
* @param width
* @param height
*/
@SuppressWarnings("unchecked")
private void cacheData(int width, int height)
{
MeasuredData md = new MeasuredData();
md.contentList = (ArrayList<LINE>) contentList.clone();
md.textSize = this.getTextSize();
md.lineWidthMax = lineWidthMax;
md.oneLineWidth = oneLineWidth;
md.measuredHeight = height;
md.width = width;
md.hashIndex = ++hashIndex;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < contentList.size(); i++)
{
LINE line = contentList.get(i);
sb.append(line.toString());
}
SoftReference<MeasuredData> cache = new SoftReference<MeasuredData>(md);
measuredData.put(text.toString(), cache);
}
/**
* 用本函式代替{@link #setText(CharSequence)}
* @param cs
*/
public void setMText(CharSequence cs)
{
text = cs;
obList.clear();
ArrayList<SpanObject> isList = new ArrayList<MTextView.SpanObject>();
useDefault = false;
if (cs instanceof SpannableString)
{
SpannableString ss = (SpannableString) cs;
CharacterStyle[] spans = ss.getSpans(0, ss.length(), CharacterStyle.class);
for (int i = 0; i < spans.length; i++)
{
int s = ss.getSpanStart(spans[i]);
int e = ss.getSpanEnd(spans[i]);
SpanObject iS = new SpanObject();
iS.span = spans[i];
iS.start = s;
iS.end = e;
iS.source = ss.subSequence(s, e);
isList.add(iS);
}
}
//對span進行排序，以免不同種類的span位置錯亂
SpanObject[] spanArray = new SpanObject[isList.size()];
isList.toArray(spanArray);
Arrays.sort(spanArray,0,spanArray.length,new SpanObjectComparator());
isList.clear();
for(int i=0;i<spanArray.length;i++)
{
isList.add(spanArray[i]);
}
String str = cs.toString();
for (int i = 0, j = 0; i < cs.length(); )
{
if (j < isList.size())
{
SpanObject is = isList.get(j);
if (i < is.start)
{
Integer cp = str.codePointAt(i);
//支援增補字元
if (Character.isSupplementaryCodePoint(cp))
{
i += 2;
}
else
{
i++;
}
obList.add(new String(Character.toChars(cp)));
}
else if (i >= is.start)
{
obList.add(is);
j++;
i = is.end;
}
}
else
{
Integer cp = str.codePointAt(i);
if (Character.isSupplementaryCodePoint(cp))
{
i += 2;
}
else
{
i++;
}
obList.add(new String(Character.toChars(cp)));
}
}
requestLayout();
}
public void setUseDefault(boolean useDefault)
{
this.useDefault = useDefault;
if (useDefault)
{
this.setText(text);
this.setTextColor(textColor);
}
}
/**
* 設定行距
* @param lineSpacingDP 行距，單位dp
*/
public void setLineSpacingDP(int lineSpacingDP)
{
this.lineSpacingDP = lineSpacingDP;
lineSpacing = dip2px(context, lineSpacingDP);
}
/**
* 獲取行距
* @return 行距，單位dp
*/
public int getLineSpacingDP()
{
return lineSpacingDP;
}
/**
* @author huangwei
* @version SocialClient 1.2.0
* @功能: 儲存Span物件及相關資訊
* @2014年5月27日
* @下午5:21:37
*/
class SpanObject
{
public Object span;
public int start;
public int end;
public CharSequence source;
}
/**
* @功能: 對SpanObject進行排序
* @author huangwei
* @2014年6月4日
* @下午5:21:30
* @version SocialClient 1.2.0
*/
class SpanObjectComparator implements Comparator<SpanObject>
{
@Override
public int compare(SpanObject lhs, SpanObject rhs)
{
return lhs.start - rhs.start;
}
}
/**
* @author huangwei
* @version SocialClient 1.2.0
* @功能: 儲存測量好的一行資料
* @2014年5月27日
* @下午5:22:12
*/
class LINE
{
public ArrayList<Object> line = new ArrayList<Object>();
public ArrayList<Integer> widthList = new ArrayList<Integer>();
public int height;
@Override
public String toString()
{
StringBuilder sb = new StringBuilder("height:" + height + " ");
for (int i = 0; i < line.size(); i++)
{
sb.append(line.get(i) + ":" + widthList.get(i));
}
return sb.toString();
}
}
/**
* @author huangwei
* @version SocialClient 1.2.0
* @功能: 快取的資料
* @2014年5月27日
* @下午5:22:25
*/
class MeasuredData
{
public int measuredHeight;
public float textSize;
public int width;
public float lineWidthMax;
public int oneLineWidth;
public int hashIndex;
ArrayList<LINE> contentList;
}
為方便在ListView中使用（ListView反覆上下滑動會多次重新onMeasure）,加了快取，相同的情況下可以不用重複在測量一次。
對於SpannableString，只支援了ImageSpan，有其它需要者可自行擴充套件
或：