问题
A hopefully quick question, but I can't seem to find any examples... I'd like to write multi-line text to a custom View via a Canvas, and in onDraw() I have:
...
String text = "This is\nmulti-line\ntext";
canvas.drawText(text, 100, 100, mTextPaint);
...
I was hoping this would result in line breaks, but instead I am seeing cryptic characters where the \n would be.
Any pointers appreciated.
Paul
回答1:
Unfortunately Android doesn't know what \n is. What you have to do is strip the \n and then offset the Y to get your text on the next line. So something like this:
canvas.drawText("This is", 100, 100, mTextPaint);
canvas.drawText("multi-line", 100, 150, mTextPaint);
canvas.drawText("text", 100, 200, mTextPaint);
回答2:
I found another way using static layouts. The code is here for anyone to refer to:
TextPaint mTextPaint=new TextPaint();
StaticLayout mTextLayout = new StaticLayout(mText, mTextPaint, canvas.getWidth(), Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);
canvas.save();
// calculate x and y position where your text will be placed
textX = ...
textY = ...
canvas.translate(textX, textY);
mTextLayout.draw(canvas);
canvas.restore();
回答3:
Just iterate through each line:
int x = 100, y = 100;
for (String line: text.split("\n")) {
canvas.drawText(line, x, y, mTextPaint);
y += mTextPaint.descent() - mTextPaint.ascent();
}
回答4:
I have written complete example
colors.xml
<color name="transparentBlack">#64000000</color>
java class
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Bitmap bm = BitmapFactory.decodeResource(getResources(), R.drawable.amit);
ImageView imageView = (ImageView)findViewById(R.id.imageView);
imageView.setImageBitmap(drawTextToBitmap(this, bm, "Name: Kolala\nDate: Dec 23 2016 12:47 PM, \nLocation: 440 Banquets & Restaurents"));
}
public Bitmap drawTextToBitmap(Context gContext,
Bitmap bitmap,
String gText) {
Resources resources = gContext.getResources();
float scale = resources.getDisplayMetrics().density;
android.graphics.Bitmap.Config bitmapConfig =
bitmap.getConfig();
// set default bitmap config if none
if(bitmapConfig == null) {
bitmapConfig = android.graphics.Bitmap.Config.ARGB_8888;
}
// resource bitmaps are imutable,
// so we need to convert it to mutable one
bitmap = bitmap.copy(bitmapConfig, true);
Canvas canvas = new Canvas(bitmap);
// new antialised Paint
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
// text color - #3D3D3D
paint.setColor(Color.WHITE);
// text size in pixels
paint.setTextSize((int) (25 * scale));
// text shadow
paint.setShadowLayer(1f, 0f, 1f, Color.WHITE);
// draw text to the Canvas center
Rect bounds = new Rect();
int noOfLines = 0;
for (String line: gText.split("\n")) {
noOfLines++;
}
paint.getTextBounds(gText, 0, gText.length(), bounds);
int x = 20;
int y = (bitmap.getHeight() - bounds.height()*noOfLines);
Paint mPaint = new Paint();
mPaint.setColor(getResources().getColor(R.color.transparentBlack));
int left = 0;
int top = (bitmap.getHeight() - bounds.height()*(noOfLines+1));
int right = bitmap.getWidth();
int bottom = bitmap.getHeight();
canvas.drawRect(left, top, right, bottom, mPaint);
for (String line: gText.split("\n")) {
canvas.drawText(line, x, y, paint);
y += paint.descent() - paint.ascent();
}
return bitmap;
}
}
回答5:
This is my solution that is based on @Dave's answer (thanks btw ;-) )
import android.graphics.Canvas;
import android.graphics.Paint;
public class mdCanvas
{
private Canvas m_canvas;
public mdCanvas(Canvas canvas)
{
m_canvas = canvas;
}
public void drawMultiline(String str, int x, int y, Paint paint)
{
for (String line: str.split("\n"))
{
m_canvas.drawText(line, x, y, paint);
y += -paint.ascent() + paint.descent();
}
}
}
I tried to inherit Canvas, but it doesn't really let you. So this is an in-between class!
回答6:
I have to add here my version which considers STROKE WIDTH as well.
void drawMultiLineText(String str, float x, float y, Paint paint, Canvas canvas) {
String[] lines = str.split("\n");
float txtSize = -paint.ascent() + paint.descent();
if (paint.getStyle() == Style.FILL_AND_STROKE || paint.getStyle() == Style.STROKE){
txtSize += paint.getStrokeWidth(); //add stroke width to the text size
}
float lineSpace = txtSize * 0.2f; //default line spacing
for (int i = 0; i < lines.length; ++i) {
canvas.drawText(lines[i], x, y + (txtSize + lineSpace) * i, paint);
}
}
回答7:
Yes. Use canvas.getFontSpacing() as the increment. I've tried it myself out of curiosity and it works for any font-size.
回答8:
try this
Paint paint1 = new Paint();
paint1.setStyle(Paint.Style.FILL);
paint1.setAntiAlias(true);
paint1.setColor(Color.BLACK);
paint1.setTextSize(15);
TextView tv = new TextView(context);
tv.setTextColor(Color.BLACK);
LinearLayout.LayoutParams llp = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
llp.setMargins(5, 2, 0, 0); // llp.setMargins(left, top, right, bottom);
tv.setLayoutParams(llp);
tv.setTextSize(10);
String text="this is good to see you , i am the king of the team";
tv.setText(text);
tv.setDrawingCacheEnabled(true);
tv.measure(MeasureSpec.makeMeasureSpec(canvas.getWidth(), MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(canvas.getHeight(), MeasureSpec.EXACTLY));
tv.layout(0, 0, tv.getMeasuredWidth(), tv.getMeasuredHeight());
canvas.drawBitmap(tv.getDrawingCache(), 5, 10, paint1);
tv.setDrawingCacheEnabled(false);
回答9:
it will work. i tested
public Bitmap drawMultilineTextToBitmap(Context gContext,
int gResId,
String gText) {
// prepare canvas
Resources resources = gContext.getResources();
float scale = resources.getDisplayMetrics().density;
Bitmap bitmap = BitmapFactory.decodeResource(resources, gResId);
android.graphics.Bitmap.Config bitmapConfig = bitmap.getConfig();
// set default bitmap config if none
if(bitmapConfig == null) {
bitmapConfig = android.graphics.Bitmap.Config.ARGB_8888;
}
// resource bitmaps are imutable,
// so we need to convert it to mutable one
bitmap = bitmap.copy(bitmapConfig, true);
Canvas canvas = new Canvas(bitmap);
// new antialiased Paint
TextPaint paint=new TextPaint(Paint.ANTI_ALIAS_FLAG);
// text color - #3D3D3D
paint.setColor(Color.rgb(61, 61, 61));
// text size in pixels
paint.setTextSize((int) (14 * scale));
// text shadow
paint.setShadowLayer(1f, 0f, 1f, Color.WHITE);
// set text width to canvas width minus 16dp padding
int textWidth = canvas.getWidth() - (int) (16 * scale);
// init StaticLayout for text
StaticLayout textLayout = new StaticLayout(
gText, paint, textWidth, Layout.Alignment.ALIGN_CENTER, 1.0f, 0.0f, false);
// get height of multiline text
int textHeight = textLayout.getHeight();
// get position of text's top left corner
float x = (bitmap.getWidth() - textWidth)/2;
float y = (bitmap.getHeight() - textHeight)/2;
// draw text to the Canvas center
canvas.save();
canvas.translate(x, y);
textLayout.draw(canvas);
canvas.restore();
return bitmap;
}
Source : http://www.skoumal.net/en/android-drawing-multiline-text-on-bitmap/
回答10:
I re-used the solution proposed by GreenBee and made a function to draw some multi line text into specified bounds with the "..." at the end if a truncate happened:
public static void drawMultiLineEllipsizedText(final Canvas _canvas, final TextPaint _textPaint, final float _left,
final float _top, final float _right, final float _bottom, final String _text) {
final float height = _bottom - _top;
final StaticLayout measuringTextLayout = new StaticLayout(_text, _textPaint, (int) Math.abs(_right - _left),
Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);
int line = 0;
final int totalLineCount = measuringTextLayout.getLineCount();
for (line = 0; line < totalLineCount; line++) {
final int lineBottom = measuringTextLayout.getLineBottom(line);
if (lineBottom > height) {
break;
}
}
line--;
if (line < 0) {
return;
}
int lineEnd;
try {
lineEnd = measuringTextLayout.getLineEnd(line);
} catch (Throwable t) {
lineEnd = _text.length();
}
String truncatedText = _text.substring(0, Math.max(0, lineEnd));
if (truncatedText.length() < 3) {
return;
}
if (truncatedText.length() < _text.length()) {
truncatedText = truncatedText.substring(0, Math.max(0, truncatedText.length() - 3));
truncatedText += "...";
}
final StaticLayout drawingTextLayout = new StaticLayout(truncatedText, _textPaint, (int) Math.abs(_right
- _left), Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);
_canvas.save();
_canvas.translate(_left, _top);
drawingTextLayout.draw(_canvas);
_canvas.restore();
}
回答11:
Solution without StaticLayout
//Get post text
String text = post.getText();
//Get weight of space character in px
float spaceWeight = paint.measureText(" ");
//Start main algorithm of drawing words on canvas
//Split text to words
for (String line : text.split(" ")) {
//If we had empty space just continue
if (line.equals("")) continue;
//Get weight of the line
float lineWeight = paint.measureText(line);
//If our word(line) doesn't have any '\n' we do next
if (line.indexOf('\n') == -1) {
//If word can fit into current line
if (cnv.getWidth() - pxx - defaultMargin >= lineWeight) {
//Draw text
cnv.drawText(line, pxx, pxy, paint);
//Move start x point to word weight + space weight
pxx += lineWeight + spaceWeight;
} else {
//If word can't fit into current line
//Move x point to start
//Move y point to the next line
pxx = defaultMargin;
pxy += paint.descent() - paint.ascent();
//Draw
cnv.drawText(line, pxx, pxy, paint);
//Move x point to word weight + space weight
pxx += lineWeight + spaceWeight;
}
//If line contains '\n'
} else {
//If '\n' is on the start of the line
if (line.indexOf('\n') == 0) {
pxx = defaultMargin;
pxy += paint.descent() - paint.ascent();
cnv.drawText(line.replaceAll("\n", ""), pxx, pxy, paint);
pxx += lineWeight + spaceWeight;
} else {
//If '\n' is somewhere in the middle
//and it also can contain few '\n'
//Split line to sublines
String[] subline = line.split("\n");
for (int i = 0; i < subline.length; i++) {
//Get weight of new word
lineWeight = paint.measureText(subline[i]);
//If it's empty subline that's mean that we have '\n'
if (subline[i].equals("")) {
pxx = defaultMargin;
pxy += paint.descent() - paint.ascent();
cnv.drawText(subline[i], pxx, pxy, paint);
continue;
}
//If we have only one word
if (subline.length == 1 && i == 0) {
if (cnv.getWidth() - pxx >= lineWeight) {
cnv.drawText(subline[0], pxx, pxy, paint);
pxx = defaultMargin;
pxy += paint.descent() - paint.ascent();
} else {
pxx = defaultMargin;
pxy += paint.descent() - paint.ascent();
cnv.drawText(subline[0], pxx, pxy, paint);
pxx = defaultMargin;
pxy += paint.descent() - paint.ascent();
}
continue;
}
//If we have set of words separated with '\n'
//it is the first word
//Make sure we can put it into current line
if (i == 0) {
if (cnv.getWidth() - pxx >= lineWeight) {
cnv.drawText(subline[0], pxx, pxy, paint);
pxx = defaultMargin;
} else {
pxx = defaultMargin;
pxy += paint.descent() - paint.ascent();
cnv.drawText(subline[0], pxx, pxy, paint);
pxx = defaultMargin;
}
} else {
pxx = defaultMargin;
pxy += paint.descent() - paint.ascent();
cnv.drawText(subline[i], pxx, pxy, paint);
pxx += lineWeight + spaceWeight;
}
}
}
}
}
回答12:
I worked with what I had, which already converted single lines to canvases, and I worked off Lumis's answer, and I ended up with this. The 1.3 and 1.3f are meant as padding between lines, relative to the size of the font.
public static Bitmap getBitmapFromString(final String text, final String font, int textSize, final int textColor)
{
String lines[] = text.split("\n");
textSize = getRelX(textSize); //a method in my app that adjusts the font size relative to the screen size
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setTextSize(textSize);
paint.setColor(textColor);
paint.setTextAlign(Paint.Align.LEFT);
Typeface face = Typeface.createFromAsset(GameActivity.getContext().getAssets(),GameActivity.getContext().getString(R.string.font) + font + GameActivity.getContext().getString(R.string.font_ttf));
paint.setTypeface(face);
float baseline = -paint.ascent(); // ascent() is negative
int width = (int) (paint.measureText(text) + 0.5f); // round
int height = (int) (baseline + paint.descent() + 0.5f);
Bitmap image = Bitmap.createBitmap(width, (int)(height * 1.3 * lines.length), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(image);
for (int i = 0; i < lines.length; ++i)
{
canvas.drawText(lines[i], 0, baseline + textSize * 1.3f * i, paint);
}
return image;
}
回答13:
My example with Dynamic Text Sizing and spacing, Works great for me...
public Bitmap fontTexture(String string, final Context context) {
float text_x = 512;
float text_y = 512;
final float scale = context.getResources().getDisplayMetrics().density;
int mThreshold = (int) (THRESHOLD_DIP * scale + 0.5f);
String[] splited = string.split("\\s+");
double longest = 0;
for(String s:splited){
if (s.length() > longest) {
longest = s.length();
}
}
if(longest > MAX_STRING_LENGTH) {
double ratio = (double) MAX_STRING_LENGTH / longest;
mThreshold = (int) ((THRESHOLD_DIP * ((float) ratio)) * scale + 0.5f);
}
Bitmap bitmap = Bitmap.createBitmap(1024, 1024, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
Typeface font = Typeface.createFromAsset(context.getAssets(),
"fonts/dotted_font.ttf");
TextPaint mTextPaint=new TextPaint();
mTextPaint.setColor(Color.YELLOW);
mTextPaint.setTextAlign(Paint.Align.CENTER);
mTextPaint.setTextSize(mThreshold);
mTextPaint.setTypeface(font);
StaticLayout mTextLayout = new StaticLayout(string, mTextPaint, canvas.getWidth(), Layout.Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);
canvas.save();
canvas.translate(text_x, text_y);
mTextLayout.draw(canvas);
canvas.restore();
return bitmap;
}
来源：https://stackoverflow.com/questions/6756975/draw-multi-line-text-to-canvas