I want to invert colors of black and white image and present that inversion as animation.
Animation should go from white background to black (black background white car), and then revert back to white (white background, black car).
You can see images here:
I tried to use ColorMatrixColorFilter like this:
final ValueAnimator colorAnim = ValueAnimator.ofInt(0, 255);
colorAnim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator animation) {
int color = (int) animation.getAnimatedValue();
float[] NEGATIVE = {
-1.0f, 0, 0, 0, color, // red
0, -1.0f, 0, 0, color, // green
0, 0, -1.0f, 0, color, // blue
0, 0, 0, 1.0f, 1 // alpha
};
v.setColorFilter(new ColorMatrixColorFilter(NEGATIVE));
}
});
But it won't return to default image (white background, black car).
Calculation is not good.
How to calculate proper values?
I tried to find how to do this, but I did not find anything useful.
Thanks!
Did you try :
1) From loaded image, create two bitmap copies into variables eg: bmp_original and bmp_negative.
2) Apply the ColorMatrix to the bitmap called bmp_negative.
3) Create a function that fades between the two bitmaps (or fades their containers).
This is better than trying to recover original colours via ColorMatrix (wrong tool). For inverted colours it's better to use a For loop to check and change the RGB values of each pixel.
In the end, it is easier and more efficient to keep a copy of original and flip between original and effected, than to try and re-calculate original colors (which you already had before the effect).
I want to create a rounded graph that will display a range of values from my app. The values can be classified to 3 categories: low, mid, high - that are represented by 3 colors: blue, green and red (respectively).
Above this range, I want to show the actually measured values - in a form of a "thumb" over the relevant range part:
The location of the white thumb over the range arc may change, according to the measured values.
Currently, I'm able to draw the 3-colored range by drawing 3 arcs over the same center, inside the view's onDraw method:
width = (float) getWidth();
height = (float) getHeight();
float radius;
if (width > height) {
radius = height / 3;
} else {
radius = width / 3;
}
paint.setAntiAlias(true);
paint.setStrokeWidth(arcLineWidth);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStyle(Paint.Style.STROKE);
center_x = width / 2;
center_y = height / 1.6f;
left = center_x - radius;
float top = center_y - radius;
right = center_x + radius;
float bottom = center_y + radius;
oval.set(left, top, right, bottom);
//blue arc
paint.setColor(colorLow);
canvas.drawArc(oval, 135, 55, false, paint);
//red arc
paint.setColor(colorHigh);
canvas.drawArc(oval, 350, 55, false, paint);
//green arc
paint.setColor(colorNormal);
canvas.drawArc(oval, 190, 160, false, paint);
And this is the result arc:
My question is, how do I:
Create a smooth gradient between those 3 colors (I tried using
SweepGradient but it didn't give me the correct result).
Create the overlay white thumb as shown in the picture, so that I'll be able to control where to display it.
Animate this white thumb over my range arc.
Note: the 3-colored range is static - so another solution can be to just take the drawable and paint the white thumb over it (and animate it), so I'm open to hear such a solution as well :)
I would use masks for your first two problems.
1. Create a smooth gradient
The very first step would be drawing two rectangles with a linear gradient. The first
rectangle contains the colors blue and green while the second rectangle contains green
and red as seen in the following picture. I marked the line where both rectangles touch each other
black to clarify that they are infact two different rectangles.
This can be achieved using the following code (excerpt):
// Both color gradients
private Shader shader1 = new LinearGradient(0, 400, 0, 500, Color.rgb(59, 242, 174), Color.rgb(101, 172, 242), Shader.TileMode.CLAMP);
private Shader shader2 = new LinearGradient(0, 400, 0, 500, Color.rgb(59, 242, 174), Color.rgb(255, 31, 101), Shader.TileMode.CLAMP);
private Paint paint = new Paint();
// ...
#Override
protected void onDraw(Canvas canvas) {
float width = 800;
float height = 800;
float radius = width / 3;
// Arc Image
Bitmap.Config conf = Bitmap.Config.ARGB_8888; // See other config types
Bitmap mImage = Bitmap.createBitmap(800, 800, conf); // This creates a mutable bitmap
Canvas imageCanvas = new Canvas(mImage);
// Draw both rectangles
paint.setShader(shader1);
imageCanvas.drawRect(0, 0, 400, 800, paint);
paint.setShader(shader2);
imageCanvas.drawRect(400, 0, 800, 800, paint);
// /Arc Image
// Draw the rectangle image
canvas.save();
canvas.drawBitmap(mImage, 0, 0, null);
canvas.restore();
}
As your goal is having a colored arc with rounded caps, we next need to define the area of
both rectangles that should be visible to the user. This means that most of both rectangles
will be masked away and thus not visible. Instead the only thing to remain is the arc area.
The result should look like this:
In order to achieve the needed behavior we define a mask that only reveals the arc area within
the rectangles. For this we make heavy use of the setXfermode method of Paint. As argument
we use different instances of a PorterDuffXfermode.
private Paint maskPaint;
private Paint imagePaint;
// ...
// To be called within all constructors
private void init() {
// I encourage you to research what this does in detail for a better understanding
maskPaint = new Paint();
maskPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
imagePaint = new Paint();
imagePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OVER));
}
#Override
protected void onDraw(Canvas canvas) {
// #step1
// Mask
Bitmap mMask = Bitmap.createBitmap(800, 800, conf);
Canvas maskCanvas = new Canvas(mMask);
paint.setColor(Color.WHITE);
paint.setShader(null);
paint.setStrokeWidth(70);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setAntiAlias(true);
final RectF oval = new RectF();
center_x = 400;
center_y = 400;
oval.set(center_x - radius,
center_y - radius,
center_x + radius,
center_y + radius);
maskCanvas.drawArc(oval, 135, 270, false, paint);
// /Mask
canvas.save();
// This is new compared to step 1
canvas.drawBitmap(mMask, 0, 0, maskPaint);
canvas.drawBitmap(mImage, 0, 0, imagePaint); // Notice the imagePaint instead of null
canvas.restore();
}
2. Create the overlay white thumb
This solves your first problem. The second one can be achieved using masks again, though this
time we want to achieve something different. Before, we wanted to show only a specific area (the arc)
of the background image (being the two rectangles). This time we want to do the opposite:
We define a background image (the thumb) and mask away its inner content, so that only
the stroke seems to remain. Applied to the arc image the thumb overlays the colored arc with
a transparent content area.
So the first step would be drawing the thumb. We use an arc for this with the same radius as
the background arc but different angles, resulting in a much smaller arc. But becaus the
thumb should "surround" the background arc, its stroke width has to be bigger than the
background arc.
#Override
protected void onDraw(Canvas canvas) {
// #step1
// #step2
// Thumb Image
mImage = Bitmap.createBitmap(800, 800, conf);
imageCanvas = new Canvas(mImage);
paint.setColor(Color.WHITE);
paint.setStrokeWidth(120);
final RectF oval2 = new RectF();
center_x = 400;
center_y = 400;
oval2.set(center_x - radius,
center_y - radius,
center_x + radius,
center_y + radius);
imageCanvas.drawArc(oval2, 270, 45, false, paint);
// /Thumb Image
canvas.save();
canvas.drawBitmap(RotateBitmap(mImage, 90f), 0, 0, null);
canvas.restore();
}
public static Bitmap RotateBitmap(Bitmap source, float angle)
{
Matrix matrix = new Matrix();
matrix.postRotate(angle);
return Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(), matrix, true);
}
The result of the code is shown below.
So now that we have a thumb that is overlaying the background arc, we need to define the mask
that removes the inner part of the thumb, so that the background arc becomes visible again.
To achieve this we basically use the same parameters as before to create another arc, but
this time the stroke width has to be identical to the width used for the background arc as
this marks the area we want to remove inside the thumb.
Using the following code, the resulting image is shown in picture 4.
#Override
protected void onDraw(Canvas canvas) {
// #step1
// #step2
// Thumb Image
// ...
// /Thumb Image
// Thumb Mask
mMask = Bitmap.createBitmap(800, 800, conf);
maskCanvas = new Canvas(mMask);
paint.setColor(Color.WHITE);
paint.setStrokeWidth(70);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
final RectF oval3 = new RectF();
center_x = 400;
center_y = 400;
oval3.set(center_x - radius,
center_y - radius,
center_x + radius,
center_y + radius);
maskCanvas.drawBitmap(mImage, 0, 0, null);
maskCanvas.drawArc(oval3, 270, 45, false, paint);
// /Thumb Mask
canvas.save();
canvas.drawBitmap(RotateBitmap(mMask, 90f), 0, 0, null); // Notice mImage changed to mMask
canvas.restore();
}
3. Animate the white thumb
The last part of your question would be animating the movement of the arc. I have no solid
solution for this, but maybe can guide you in a useful direction. I would try the following:
First define the thumb as a ImageView that is part of your whole arc graph. When changing
the selected values of your graph, you rotate the thumb image around the center of the background
arc. Because we want to animate the movement, just setting the rotation of the thumb image would
not be adequate. Instead we use a RotateAnimation kind of like so:
final RotateAnimation animRotate = new RotateAnimation(0.0f, -90.0f, // You have to replace these values with your calculated angles
RotateAnimation.RELATIVE_TO_SELF, // This may be a tricky part. You probably have to change this to RELATIVE_TO_PARENT
0.5f, // x pivot
RotateAnimation.RELATIVE_TO_SELF,
0.5f); // y pivot
animRotate.setDuration(1500);
animRotate.setFillAfter(true);
animSet.addAnimation(animRotate);
thumbView.startAnimation(animSet);
This is far from final I guess, but it very well may aid you in your search for the needed
solution. It is very important that your pivot values have to refer to the center of your
background arc as this is the point your thumb image should rotate around.
I have tested my (full) code with API Level 16 and 22, 23, so I hope that this answer at least
gives you new ideas on how to solve your problems.
Please note that allocation operations within the onDraw method are a bad idea and should
be avoided. For simplicity I failed to follow this advise. Also the code is to be used as
a guide in the right direction and not to be simply copy & pasted, because it makes heavy
use of magic numbers and generally does not follow good coding standards.
I would change a bit of the way you draw your view, by looking on the original design, instead of drawing 3 caps I would draw just 1 line, that way the SweepGradient will work.
This migth be a bit tricky, you have 2 options:
create a Path with 4 arcs
draw 2 arcs- one is the big white (filled with white so you still want to use Paint.Style.STROKE) and another on top of that make it fill transparent, you can achieve it with PorterDuff xfermode, it probably take you couple of tries until you get that without clearing the green circle too.
I imagine you want to animate thumb position, so just use simple Animation that invalidate the view and draw the thumb view position accordingly.
Hopes this helps
Create a gradient than follow a path is not so simple.
So I can suggest you to use some libraries than already did it.
Include the library:
dependencies {
...
compile 'com.github.paroca72:sc-gauges:3.0.7'
}
Create the gauge in XML:
<com.sccomponents.gauges.library.ScArcGauge
android:id="#+id/gauge"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal" />
Your code:
ScArcGauge gauge = this.findViewById(R.id.gauge);
gauge.setAngleSweep(270);
gauge.setAngleStart(135);
gauge.setHighValue(90);
int lineWidth = 50;
ScCopier baseLine = gauge.getBase();
baseLine.setWidths(lineWidth);
baseLine.setColors(Color.parseColor("#dddddd"));
baseLine.getPainter().setStrokeCap(Paint.Cap.ROUND);
ScCopier progressLine = gauge.getProgress();
progressLine.setWidths(lineWidth);
progressLine.setColors(
Color.parseColor("#65AAF2"),
Color.parseColor("#3EF2AD"),
Color.parseColor("#FF2465")
);
progressLine.getPainter().setStrokeCap(Paint.Cap.ROUND);
Your result:
You can find something more complex on this site:
ScComponents
Ok so I want to have a bitmap where it is invisible but if you touch it, then the area that is touched will show. This might not seem useful by itself, but I just want to know how to do it so I can apply it to what I really want to do. So how would you do this in android where you only draw certain pixels of a bitmap?
A good starting point would be Roman Guy's "Fun with shaders" recipe, which should get you pretty close:
Thus by moving a shape over the canvas you can reveal different parts of the bitmap.
The basic steps include:
Create an alpha mask (the linked example uses another bitmap for this):
private static Bitmap convertToAlphaMask(Bitmap b) {
Bitmap a = Bitmap.createBitmap(b.getWidth(), b.getHeight(), Bitmap.Config.ALPHA_8);
Canvas c = new Canvas(a);
c.drawBitmap(b, 0.0f, 0.0f, null);
return a;
}
Bitmap mask;
mask = convertToAlphaMask(BitmapFactory.decodeResource(getResources(), R.drawable.spot_mask));
Create a Paint instance with a shader to draw the mask with:
private static Shader createShader(Bitmap b) {
return new BitmapShader(b, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
}
Shader targetShader = createShader(mTargetBitmap);
paint.setShader(targetShader);
Finally, draw the mask with the shader:
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(mMask, 0.0f, 0.0f, mPaint);
}
Now, in stead of animating the 'light beam' over a predefined path (as in the example code), hook it up to touch events and go from there. I.e. you may have to keep track of the touched areas and/or paths to get the desired effect.
I'm doing a Live Wallpaper. I have a Runnable (which is updated every 5 seconds) where I call a draw() method which draws something on a Canvas. It calls a method in another class which is supposed to draw a series of bitmaps (with a delay, so it's animated). How would I change the code below, so that the next bitmap would be drawn with a delay?
int imageToDraw = 10;
while(imageToDraw>=0)
{
Bitmap b = BitmapFactory.decodeResource(mContext.getResources(), mContext.getResources().getIdentifier("image_"+imageToDraw, "raw", mContext.getPackageName()));
float centerX = (width - b.getWidth())/2;
float centerY = (height - b.getHeight())/2;
Paint p = new Paint();
p.setColor(Color.BLACK);
mCanvas.drawRect(0f, 0f, (float)width, (float)height, p); //draws a rectangle to clear the screen
mCanvas.drawBitmap(b, centerX, centerY, new Paint());
--imageToDraw;
b.recycle();
}
From Android's API Guide on Canvas and Drawables:
Draw your graphics directly to a Canvas. This way, you personally call
the appropriate class's onDraw() method (passing it your Canvas), or
one of the Canvas draw...() methods (like drawPicture()). In doing so,
you are also in control of any animation.
This means you have to perform the animation yourself, frame by frame. If you don't actually need to draw complex graphics, consider switching back to standard views so you can use help class like AnimationDrawable. Check here for an example of how to do your own animation in Canvas.
I get my bitmap, use it as a shader tile mode.
The PNG is mostly alpha except for the shape outline to draw.
Except it draws the outline, but is surrounded by black, not seethrough (alpha).
pnt.reset();
if(backgroundColor == 1)
{
pnt.setColor(myColor);
pnt.setStyle(Paint.Style.FILL);
}
m_canvas.drawPath(path, pnt);
//fillBMP = getBitmapFromAsset(m_context, "brush.png");
fillBMP = BitmapFactory.decodeFile(mySDPath + "brush.png");
fillBMPshader = new BitmapShader(fillBMP, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);
pnt.setShader(fillBMPshader);
m_canvas.drawPath(path, pnt);
Example below of the brush on left. But result it draws on right.
You should set XferMode on your Paint object. More specifically you got to use PorterDuffXferMode MULTIPLY.
Here is a similar question : Android color overlay - PorterDuff modes