So I know there are a lot of questions like this, but none of the answers have had any effect.
I have a custom View that I am trying to put into a ScrollView (all programmatically). The ScrollView itself works fine, is where it needs to be, does what it's supposed to do and when tested by adding a TextView to it, still did what it was supposed to.
However when I create my custom View the view doesn't draw and it is as if nothing is there. The draw(Canvas canvas) method is never called (also tried with onDraw even though I don't know what the difference is but it still didn't work).
I have tried things such as setWillNotDraw(false) in the constructor, called View.invalidate() every time I want it to draw/redraw, nothing appears to be working.
Here is the relevant code:
ScrollView Initialized
sv = new ScrollView(env.getContext());
ScaledBounds sb = UsefulMethods.getScaledBounds(50, 200, BBEnvironment.WIDTH - 100, BBEnvironment.HEIGHT - 300);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(sb.getWidth(), sb.getHeight());
sv.setTranslationX(sb.getX());
sv.setTranslationY(sb.getY());
sv.setLayoutParams(params);
sv.setScrollbarFadingEnabled(false);
sv.setScrollBarSize(0);
sv.setBackgroundColor(Color.argb(150, 0, 255, 0));
Custom View Class
private class LevelSelectionView extends View {
private ArrayList<LevelButton> levelButtons;
public LevelSelectionView(Context context) {
super(context);
levelButtons = new ArrayList<LevelButton>();
int x = 20;
int y = 20;
for(int i = 0; i < 20; i++) {
levelButtons.add(new LevelButton(x, y, 100, 100, 10, i + 1));
levelButtons.get(i).unlock();
x += 100 + 20;
}
setWillNotDraw(false);
}
public void draw(Canvas canvas) {
super.draw(canvas);
System.out.println("is being called"); //except it isn't
Paint paint = new Paint();
paint.setAntiAlias(env.getCurrentSettings().getAntialias());
for(LevelButton lb : levelButtons)
lb.drawObject(canvas, paint);
}
}
Creating and adding custom view
LevelSelectionView lsView = new LevelSelectionView(sv.getContext());
lsView.setLayoutParams(new RelativeLayout.LayoutParams(sv.getLayoutParams().width, 1000));
lsView.setBackgroundColor(Color.argb(150, 0, 0, 255));
sv.addView(lsView);
Why is it not drawing and how do I get it to draw?
I tried like that and it works:
public class LevelSelectionView extends View {
private final static String TAG = LevelSelectionView.class.getSimpleName();
private final ArrayList<Button> mButtons;
private final Paint mPaint;
public LevelSelectionView(Context context) {
super(context);
mButtons = new ArrayList<Button>();
int x = 20;
int y = 20;
mPaint = new Paint();
// mPaint.setAntiAlias(env.getCurrentSettings().getAntialias());
Button myButton;
for (int i = 0; i < 20; i++) {
myButton = new Button(context);
myButton.setLayoutParams(new ViewGroup.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.MATCH_PARENT));
mButtons.add(myButton);
// mButtons.get(i).unlock();
// x += 100 + 20;
}
setWillNotDraw(false);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (Button lb : mButtons)
Log.d(TAG, "is being called"); //except it isn't
// lb.drawObject(canvas, mPaint);
}
}
I don't know what is your LevelButton as it's a custom class.
I create the LevelSelectionView like that, using a FrameLayout but it's the same idea with the ScrollView:
FrameLayout container = (FrameLayout) findViewById(R.id.container);
LevelSelectionView view = new LevelSelectionView(this);
view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
container.addView(view);
Maybe your issue comes from the LevelButton or the context you use (as you use the Context from env to create the ScrollView and the Context of the ScrollView to create your custom class). You code is not clear as we don't know what is your env object as all your class are inner classes.
It looks like you need to properly implement onMeasure so the scrollview knows how tall that view is.
I am creating an app using portable xamarin form cross platform having android and IOS project
I want to add listview in custom dialog box. Is it possible?
If is it possible then please share the solution.
You can see example in below image
I created my base page as Absolute Layout with button. When I press button I push absolute layout PopUpListView on top. Here is the code.
On main page
class LoginPage : ContentPage
{
Button btnLogin;
AbsoluteLayout layout;
public LoginPage()
{
layout = new AbsoluteLayout
{
HorizontalOptions = LayoutOptions.FillAndExpand,
VerticalOptions = LayoutOptions.FillAndExpand,
};
BackgroundColor = Color.FromUint(0xFFDBDBDB);
btnLogin = new Button
{
HorizontalOptions = LayoutOptions.FillAndExpand,
Text = "Press me",
BackgroundColor = Color.FromUint(0xFF6E932D),
TextColor = Color.White,
};
btnLogin.Clicked += BtnLogin_Clicked;
layout.Children.Add(btnLogin, new Rectangle(0.5f, 0.1f, 0.25f, 0.25f), AbsoluteLayoutFlags.All);
Content = layout;
}
private void BtnLogin_Clicked(object sender, EventArgs e)
{
layout.Children.Add(new PopUpListView(), new Rectangle(0, 0, 1, 1), AbsoluteLayoutFlags.All);
}
}
And here is your Popoup
public class PopUpListView : AbsoluteLayout
{
public PopUpListView()
{
BackgroundColor = Color.FromRgba(0, 0, 0, 0.4);
var list = new MyListView();
Children.Add(list, new Rectangle(0.5f, 0.5f, 0.5f, 0.5f), AbsoluteLayoutFlags.All);
}
}
class MyListView : ListView
{
public MyListView()
{
BackgroundColor = Color.Black;
ItemsSource =new string[] {"1 choice", "2 choice", "3 choice" };
}
}
I want to create a single drawable that shows two lines of text, one above the other. Each line of text has to be in it's own typeface and textsize and it has to create a single drawable because I want to then set it as the drawable for a floating action button.
private void updateFloatingButtonText(String headlineText, String subHeadlineText, FloatingActionButton floatingActionButton) {
int headlineTextSize = getResources().getDimensionPixelSize(R.dimen.headlineTextSize);
int subheadlineTextSize = getResources().getDimensionPixelSize(R.dimen.subheadlineTextSize);
Spannable spannableStringHeadline = new SpannableString(headlineText);
Spannable spannableStringSubheadline = new SpannableString(subHeadlineText);
CustomTypefaceSpan boldSpan = new CustomTypefaceSpan("FontOne", FontCache.get("FontOne.ttf", this));
CustomTypefaceSpan regularSpan = new CustomTypefaceSpan("FontTwo", FontCache.get("FontTwo.ttf", this));
// set typeface headline
spannableStringHeadline.setSpan(regularSpan, 0,
headlineText.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE
);
// set typeface subtitle
spannableStringSubheadline.setSpan(boldSpan, 0,
subHeadlineText.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE
);
// set text size headline
spannableStringHeadline.setSpan(new AbsoluteSizeSpan(headlineTextSize), 0,
headlineText.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE
);
// set text size subline
spannableStringSubheadline.setSpan(new AbsoluteSizeSpan(subheadlineTextSize), 0,
subHeadlineText.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE
);
String finalString = TextUtils.concat(spannableStringHeadline, "\n", spannableStringSubheadline);
floatingActionButton.setImageDrawable([put the resulting drawable here]);
}
I've written this method that creates a single string formatted exactly the way that I need it, but I still have the issue of creating a drawable out of it.
I've tried to use this third party library, but although it displays the text in the correct typefaces it doesn't change the textsize of the lines of text.
https://github.com/devunwired/textdrawable
Is there a trivial (or nontrivial) way of doing this?
Solved by creating a new class that looks like this:
public class TextToDrawable extends Drawable {
private String headlineText = "";
private String subHeadlineText = "";
private final TextPaint headlinePaint = new TextPaint();
private final TextPaint subHeadlinePaint = new TextPaint();
public TextToDrawable(Context context, String headlineText, String subHeadlineText) {
this.headlineText = headlineText;
headlinePaint.setAntiAlias(true);
headlinePaint.setTypeface(FontCache.get("FontA.ttf", context));
headlinePaint.setTextSize(context.getResources().getDimensionPixelSize(R.dimen.headlineTextSize));
headlinePaint.setColor(ContextCompat.getColor(context, android.R.color.white));
headlinePaint.setStyle(Paint.Style.FILL);
headlinePaint.setTextAlign(Paint.Align.LEFT);
this.subHeadlineText = subHeadlineText;
subHeadlinePaint.setAntiAlias(true);
subHeadlinePaint.setTypeface(FontCache.get("FontB.ttf", context));
subHeadlinePaint.setTextSize(context.getResources().getDimensionPixelSize(R.dimen.subheadlineTextSize));
subHeadlinePaint.setColor(ContextCompat.getColor(context, android.R.color.white));
subHeadlinePaint.setStyle(Paint.Style.FILL);
subHeadlinePaint.setTextAlign(Paint.Align.LEFT);
}
#Override
public void draw(Canvas canvas) {
Rect headlineWidth = new Rect();
Rect subheadlineWidth = new Rect();
headlinePaint.getTextBounds(headlineText, 0, headlineText.length(), headlineWidth);
subHeadlinePaint.getTextBounds(subHeadlineText, 0, subHeadlineText.length(), subheadlineWidth);
Rect bounds = new Rect();
headlinePaint.getTextBounds(headlineText, 0, headlineText.length(), bounds);
int x = getBounds().width() / 2 - (headlineWidth.width()/2);
int y = (getBounds().height() / 2);
canvas.drawText(headlineText, x, y, headlinePaint);
x = getBounds().width()/2 - (subheadlineWidth.width()/2);
y += headlinePaint.getFontSpacing();
canvas.drawText(subHeadlineText, x, y, subHeadlinePaint);
}
#Override
public void setAlpha(int alpha) {
}
#Override
public void setColorFilter(ColorFilter colorFilter) {
}
#Override
public int getOpacity() {
return 0;
}
}
Then using the new class like this:
mFloatingActionButton.setImageDrawable(new TextToDrawable(this, "Headline", "Subheadline"));
This isn't a great solution because it only supports two lines of text - there's nothing dynamic going on here. However, I suppose it would be fairly easy to rewrite to support even more lines and more fonts and it solves the current problem.
How would I extend TextView to allow the drawing of text with a gradient effect?
TextView secondTextView = new TextView(this);
Shader textShader=new LinearGradient(0, 0, 0, 20,
new int[]{Color.GREEN,Color.BLUE},
new float[]{0, 1}, TileMode.CLAMP);
secondTextView.getPaint().setShader(textShader);
I have used the top answer(#Taras) with a gradient of 5 colors, but there is a problem: the textView looks like that I have put a white cover on it. Here is my code and the screenshot.
textView = (TextView) findViewById(R.id.main_tv);
textView.setText("Tianjin, China".toUpperCase());
TextPaint paint = textView.getPaint();
float width = paint.measureText("Tianjin, China");
Shader textShader = new LinearGradient(0, 0, width, textView.getTextSize(),
new int[]{
Color.parseColor("#F97C3C"),
Color.parseColor("#FDB54E"),
Color.parseColor("#64B678"),
Color.parseColor("#478AEA"),
Color.parseColor("#8446CC"),
}, null, Shader.TileMode.CLAMP);
textView.getPaint().setShader(textShader);
After many hours, I found out that I need to call textView.setTextColor() with the first color of the gradient. Then the screenshot:
Hope help someone!
It doesn't appear possible to extend TextView to draw text with a gradient. It is, however, possible to achieve this effect by creating a canvas and drawing on it. First we need to declare our custom UI element. In the initiation we need to create a subclass of Layout. In this case, we will use BoringLayout which only supports text with a single line.
Shader textShader=new LinearGradient(0, 0, 0, 20,
new int[]{bottom,top},
new float[]{0, 1}, TileMode.CLAMP);//Assumes bottom and top are colors defined above
textPaint.setTextSize(textSize);
textPaint.setShader(textShader);
BoringLayout.Metrics boringMetrics=BoringLayout.isBoring(text, textPaint);
boringLayout=new BoringLayout(text, textPaint, 0, Layout.Alignment.ALIGN_CENTER,
0.0f, 0.0f, boringMetrics, false);
We then override onMeasure and onDraw:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
setMeasuredDimension((int) textPaint.measureText(text), (int) textPaint.getFontSpacing());
}
#Override
protected void onDraw(Canvas canvas){
super.onDraw(canvas);
boringLayout.draw(canvas);
}
Our implementation of onDraw is at this point quite lazy (it completely ignores the measurement specs!, but so long as you guarantee that the view is given sufficent space, it should work okay.
Alternatively, it would be possible to inherit from a Canvas and override the onPaint method. If this is done, then unfortunately the anchor for text being drawn will always be on the bottom so we have to add -textPaint.getFontMetricsInt().ascent() to our y coordinate.
Here it is with multiline support as a one liner. This should work for Buttons too.
Shader shader = new LinearGradient(0,0,0,textView.getLineHeight(),
startColor, endColor, Shader.TileMode.REPEAT);
textView.getPaint().setShader(shader);
I've rolled up a library that encompasses both of these methods. You can create GradientTextView in XML or just use GradientTextView.setGradient(TextView textView...) to do it on a regular TextView object.
https://github.com/koush/Widgets
A simple but somewhat limited solution would be to use these attributes:
android:fadingEdge="horizontal"
android:scrollHorizontally="true"
I have used it on textfields where I want them to fade out if they get too long.
Kotlin + coroutines version.
Extension for setting vertical gradient:
private fun TextView.setGradientTextColor(vararg colorRes: Int) {
val floatArray = ArrayList<Float>(colorRes.size)
for (i in colorRes.indices) {
floatArray.add(i, i.toFloat() / (colorRes.size - 1))
}
val textShader: Shader = LinearGradient(
0f,
0f,
0f,
this.height.toFloat(),
colorRes.map { ContextCompat.getColor(requireContext(), it) }.toIntArray(),
floatArray.toFloatArray(),
TileMode.CLAMP
)
this.paint.shader = textShader
}
Suspend extension. You need to wait for the view to change its height.
suspend fun View.awaitLayoutChange() = suspendCancellableCoroutine<Unit> { cont ->
val listener = object : View.OnLayoutChangeListener {
override fun onLayoutChange(
view: View?,
left: Int,
top: Int,
right: Int,
bottom: Int,
oldLeft: Int,
oldTop: Int,
oldRight: Int,
oldBottom: Int
) {
view?.removeOnLayoutChangeListener(this)
cont.resumeWith(Result.success(Unit))
}
}
addOnLayoutChangeListener(listener)
cont.invokeOnCancellation { removeOnLayoutChangeListener(listener) }
}
And usage:
lifecycle.coroutineScope.launch {
binding.tvAmount.text = "Dumb text"
binding.tvAmount.awaitLayoutChange()
binding.tvAmount.setGradientTextColor(
R.color.yellow,
R.color.green
)
}
For Kotlin:
val paint: TextPaint = textView.paint
val width: Float = paint.measureText(holder.langs.text.toString())
val textShader: Shader = LinearGradient(0f, 0f, width, holder.langs.textSize, intArrayOf(
Color.parseColor("#8913FC"),
Color.parseColor("#00BFFC")), null, Shader.TileMode.CLAMP)
holder.langs.paint.shader = textShader
Here's my solved way. Implement with text span.
screenshot
class LinearGradientForegroundSpan extends CharacterStyle implements UpdateAppearance {
private int startColor;
private int endColor;
private int lineHeight;
public LinearGradientForegroundSpan(int startColor, int endColor, int lineHeight) {
this.startColor = startColor;
this.endColor = endColor;
this.lineHeight = lineHeight;
}
#Override
public void updateDrawState(TextPaint tp) {
tp.setShader(new LinearGradient(0, 0, 0, lineHeight,
startColor, endColor, Shader.TileMode.REPEAT));
}
}
Styled your gradient text.
SpannableString gradientText = new SpannableString("Gradient Text");
gradientText.setSpan(new LinearGradientForegroundSpan(Color.RED, Color.LTGRAY, textView.getLineHeight()),
0, gradientText.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
SpannableStringBuilder sb = new SpannableStringBuilder();
sb.append(gradientText);
sb.append(" Normal Text");
textView.setText(sb);
Here's a nice way to do it:
/**
* sets a vertical gradient on the textView's paint, so that on its onDraw method, it will use it.
*
* #param viewAlreadyHasSize
* set to true only if the textView already has a size
*/
public static void setVerticalGradientOnTextView(final TextView tv, final int positionsAndColorsResId,
final boolean viewAlreadyHasSize) {
final String[] positionsAndColors = tv.getContext().getResources().getStringArray(positionsAndColorsResId);
final int[] colors = new int[positionsAndColors.length];
float[] positions = new float[positionsAndColors.length];
for (int i = 0; i < positionsAndColors.length; ++i) {
final String positionAndColors = positionsAndColors[i];
final int delimeterPos = positionAndColors.lastIndexOf(':');
if (delimeterPos == -1 || positions == null) {
positions = null;
colors[i] = Color.parseColor(positionAndColors);
} else {
positions[i] = Float.parseFloat(positionAndColors.substring(0, delimeterPos));
String colorStr = positionAndColors.substring(delimeterPos + 1);
if (colorStr.startsWith("0x"))
colorStr = '#' + colorStr.substring(2);
else if (!colorStr.startsWith("#"))
colorStr = '#' + colorStr;
colors[i] = Color.parseColor(colorStr);
}
}
setVerticalGradientOnTextView(tv, colors, positions, viewAlreadyHasSize);
}
/**
* sets a vertical gradient on the textView's paint, so that on its onDraw method, it will use it. <br/>
*
* #param colors
* the colors to use. at least one should exist.
* #param tv
* the textView to set the gradient on it
* #param positions
* where to put each color (fraction, max is 1). if null, colors are spread evenly .
* #param viewAlreadyHasSize
* set to true only if the textView already has a size
*/
public static void setVerticalGradientOnTextView(final TextView tv, final int[] colors, final float[] positions,
final boolean viewAlreadyHasSize) {
final Runnable runnable = new Runnable() {
#Override
public void run() {
final TileMode tile_mode = TileMode.CLAMP;
final int height = tv.getHeight();
final LinearGradient lin_grad = new LinearGradient(0, 0, 0, height, colors, positions, tile_mode);
final Shader shader_gradient = lin_grad;
tv.getPaint().setShader(shader_gradient);
}
};
if (viewAlreadyHasSize)
runnable.run();
else
runJustBeforeBeingDrawn(tv, runnable);
}
public static void runJustBeforeBeingDrawn(final View view, final Runnable runnable) {
final OnPreDrawListener preDrawListener = new OnPreDrawListener() {
#Override
public boolean onPreDraw() {
view.getViewTreeObserver().removeOnPreDrawListener(this);
runnable.run();
return true;
}
};
view.getViewTreeObserver().addOnPreDrawListener(preDrawListener);
}
Also, if you wish to use a bitmap of the gradient, instead or a real one, use:
/**
* sets an image for the textView <br/>
* NOTE: this function must be called after you have the view have its height figured out <br/>
*/
public static void setBitmapOnTextView(final TextView tv, final Bitmap bitmap) {
final TileMode tile_mode = TileMode.CLAMP;
final int height = tv.getHeight();
final int width = tv.getWidth();
final Bitmap temp = Bitmap.createScaledBitmap(bitmap, width, height, true);
final BitmapShader bitmapShader = new BitmapShader(temp, tile_mode, tile_mode);
tv.getPaint().setShader(bitmapShader);
}
EDIT: Alternative to runJustBeforeBeingDrawn: https://stackoverflow.com/a/28136027/878126
I have combined the answers from this thread and made a lightweight library. You can use it with gradle implementation, or simply use the files needed by adding it to your source.
https://github.com/veeyaarVR/SuperGradientTextView
The solution that worked for me is to apply a text color before applying any shaders. As the author of the question posted:
After many hours, I found out that I need to call textView.setTextColor() with the first color of the gradient. Then the screenshot:
What works is to have, for instance, a white color setup as text color in the first place. Then we can apply the shader, and it will be applied on top of the white so we will get the desired gradient color.
Here is an example for linearlayout, you can use this example for textview too, and in the source code there wont be gradient coding, you get the source code and add the code from that site itself - http://android-codes-examples.blogspot.com/2011/07/design-linearlayout-or-textview-and-any.html
I've found the way to do this without the TextView class extension.
class MainActivity : AppCompatActivity() {
private val textGradientOnGlobalLayoutListener = object: ViewTreeObserver.OnGlobalLayoutListener {
override fun onGlobalLayout() {
textGradient.paint.shader = LinearGradient(0f, 0f,
textGradient.width.toFloat(),
textGradient.height.toFloat(),
color0, color1, Shader.TileMode.CLAMP)
textGradient.viewTreeObserver.removeOnGlobalLayoutListener(this)
}
}
private val textGradient by lazy {
findViewById<TextView>(R.id.text_gradient)
}
private val color0 by lazy {
ContextCompat.getColor(applicationContext, R.color.purple_200)
}
private val color1 by lazy {
ContextCompat.getColor(applicationContext, R.color.teal_200)
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
textGradient.viewTreeObserver.addOnGlobalLayoutListener(textGradientOnGlobalLayoutListener)
}
}
Try
import com.sanne.MultiColorTextView;
MultiColorTextView textview= new MultiColorTextView(this);
textview.setText("SOME TEXT");
textview.setTextColor(/*INT ARRAY WITH YOUR COLOURS*/ );
The program sets a gradient colour across the textview and you can also set separate colours for particular text using
multiColorTextView.colorAll("A word");
MutliColorTextView from https://www.github.com/sanneemmanuel/MultiColorTextView