问题
THIS IS NOT ABOUT AntiAlias, Please read the question before answering thank you.
ADDING BOUNTY TO--> android convert text width (in pixels) to percent of screen width/height
Quality info --> https://stackoverflow.com/a/1016941/1815624
I am getting inconsistent results when trying to draw text on a canvas. Please help, thank you.
I want the text to consume the same amount of scaled space on all devices
I do not care about ANTI_ALIAS and have added the paint.setFlags(Paint.ANTI_ALIAS_FLAG); but the problem is the same...
On 1 screen the text consumes half the width, on another only a 1/3 and even one that uses the full width.
I want them all to use equal amounts of screen real estate.
For Example
1600X900 7inch tablet Kitkat physical:
1920.1080 5.2 kitkat physical
1600x900 20in Lollipop emulated
1280x720 4.7inch
These have been created using the guide at http://www.gkproggy.com/2013/01/draw-text-on-canvas-with-font-size.html
where as that tutorial is showing consistent results
To be thorough here is the source:
public class MainActivity extends Activity
{
Paint paint;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
paint = new Paint();
View test = new TestView(this);
setContentView(test);
}
public class TestView extends View
{
public TestView(Context context)
{
super(context);
setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
}
public float pixelsToSp(Context context, float px) {
float scaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
return px/scaledDensity;
}
public float spToPixels(float sp) {
Context context = getContext();
float scaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
return scaledDensity*sp;
}
@Override
protected void onDraw(Canvas canvas)
{
int size = getResources().getDimensionPixelSize(R.dimen.sp20);
int px = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 20, getResources().getDisplayMetrics());
Log.v("intSize", Integer.toString(size));
Log.v("intSize", Integer.toString(px));
Log.v("intSize", Float.toString(spToPixels(20f)));
if(true) {
Typeface myTypeface = Typeface.createFromAsset(getContext().getAssets(), "fonts/Ultra.ttf");
paint.setTypeface(myTypeface);
}
paint.setColor(Color.BLACK);
paint.setTextSize(size);
paint.setFlags(Paint.ANTI_ALIAS_FLAG);
canvas.drawText("HELLOOOOOOOOOOOOOO!", 0, size, paint);
super.onDraw(canvas);
}
}
}
I have tried suggestion from https://stackoverflow.com/a/5369766/1815624
Looking into this
https://stackoverflow.com/a/21895626/1815624
https://stackoverflow.com/a/14753968/1815624
https://stackoverflow.com/a/21895626/1815624 <-- trying now
回答1:
Resources used:
https://stackoverflow.com/a/4847027/1815624
https://stackoverflow.com/a/21895626/1815624
Got to get screen width, some reference of text size to screen ratio, and calculate. so the results are:
and
notice the second HELLOOOOOOOOOOOOOOOOO!
public class MainActivity extends Activity
{
Paint paint;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
paint = new Paint();
View test = new TestView(this);
setContentView(test);
}
public class TestView extends View
{
public TestView(Context context)
{
super(context);
setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
}
public float pixelsToSp(float px) {
Context context = getContext();
float scaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
return px/scaledDensity;
}
public float spToPixels(float sp) {
Context context = getContext();
float scaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
return scaledDensity*sp;
}
@Override
protected void onDraw(Canvas canvas)
{
int size = getResources().getDimensionPixelSize(R.dimen.sp20);
int px = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 20, getResources().getDisplayMetrics());
Log.v("intSize", Integer.toString(size));
Log.v("intSize", Integer.toString(px));
Log.v("intSize", Float.toString(spToPixels(20f)));
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
Log.v("intSize hm", Integer.toString(metrics.heightPixels));
Log.v("intSize wm", Integer.toString(metrics.widthPixels));
if(true) {
Typeface myTypeface = Typeface.createFromAsset(getContext().getAssets(), "fonts/Ultra.ttf");
paint.setTypeface(myTypeface);
}
paint.setColor(Color.BLACK);
paint.setTextSize(size);
paint.setFlags(Paint.ANTI_ALIAS_FLAG);
canvas.drawText("HELLOOOOOOOOOOOOOO!", 0, size, paint);
setTextSizeForWidth(paint, metrics.widthPixels * 0.5f, "HELLOOOOOOOOOOOOOO!");
canvas.drawText("HELLOOOOOOOOOOOOOO!", 0, size*3, paint);
super.onDraw(canvas);
}
/**
* Sets the text size for a Paint object so a given string of text will be a
* given width.
*
* @param paint
* the Paint to set the text size for
* @param desiredWidth
* the desired width
* @param text
* the text that should be that width
*/
private void setTextSizeForWidth(Paint paint, float desiredWidth,
String text) {
// Pick a reasonably large value for the test. Larger values produce
// more accurate results, but may cause problems with hardware
// acceleration. But there are workarounds for that, too; refer to
// https://stackoverflow.com/questions/6253528/font-size-too-large-to-fit-in-cache
final float testTextSize = 48f;
// Get the bounds of the text, using our testTextSize.
paint.setTextSize(testTextSize);
Rect bounds = new Rect();
paint.getTextBounds(text, 0, text.length(), bounds);
// Calculate the desired size as a proportion of our testTextSize.
float desiredTextSize = testTextSize * desiredWidth / bounds.width();
// Set the paint for that size.
paint.setTextSize(desiredTextSize);
}
}
}
please note if you not extending Activity use
DisplayMetrics metrics = new DisplayMetrics();
WindowManager windowManager = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
windowManager.getDefaultDisplay().getMetrics(metrics);
instead of
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
来源：https://stackoverflow.com/questions/35117278/canvas-drawtext-with-pixel-perfect-text-on-a-canvas