I'm trying to set the fill opacity of a vector feature in OL3 and can't figure out how to do it if I have a hexadecimal value...I've seen examples with rgba. Any suggestions?
Here's what I have:
style : function(feature, resolution) {
return [new ol.style.Style(
{
stroke : new ol.style.Stroke(
{
color : feature.get('color'),
width : 2
}),
fill : new ol.style.Fill(
{
color : feature.get('color'), //'#FF0000'
opacity : 0.2 // I thought this would work, but it's not an option
})
})]
}
This is late but might help someone.
Using rgba property is also possible.
fill: new ol.style.Fill({color: 'rgba(255, 255, 0, 0.63)'}),
You can use the ol.color.asArray function. That function converts color strings to color arrays.
So this is what you can use:
var hexColor = feature.get('color');
var color = ol.color.asArray(hexColor);
color = color.slice();
color[3] = 0.2; // change the alpha of the color
slice() is used to create a new color array. This is to avoid corrupting the "color strings to color arrays" cache that the ol.color.asArray function maintains.
See http://openlayers.org/en/master/apidoc/ol.color.html?unstable=true#asArray.
import ol_color from 'ol/color';
colorWithAlpha(color, alpha) {
const [r, g, b] = Array.from(ol_color.asArray(color));
return ol_color.asString([r, g, b, alpha]);
}
Related
I need to allow the user to choose a color on iOS.
I use the following code to fire up the color picker:
var picker = new UIColorPickerViewController();
picker.SupportsAlpha = true;
picker.Delegate = this;
picker.SelectedColor = color.ToUIColor();
PresentViewController(picker, true, null);
When the color picker displays, the color is always slightly off. For example:
input RGBA: (220, 235, 92, 255)
the initial color in the color picker might be:
selected color: (225, 234, 131, 255)
(these are real values from tests). Not a long way off... but enough to notice if you are looking for it.
I was wondering if the color picker grid was forcing the color to the
nearest color entry - but if that were true, you would expect certain colors to
stay fixed (i.e. if the input color exactly matches one of the grid colors,
it should stay unchanged). That does not happen.
p.s. I store colors in a cross platform fashion using simple RGBA values.
The ToUIColor converts to local UIColor using
new UIColor((nfloat)rgb.r, (nfloat)rgb.g, (nfloat)rgb.b, (nfloat)rgb.a);
From the hints in comments by #DonMag, I've got some way towards an answer, and also a set of resources that can help if you are struggling with this.
The key challenge is that mac and iOS use displayP3 as the ColorSpace, but most people use default {UI,NS,CG}Color objects, which use the sRGB ColorSpace (actually... technically they are Extended sRGB so they can cover the wider gamut of DisplayP3). If you want to know the difference between these three - there's resources below.
When you use the UIColorPickerViewController, it allows the user to choose colors in DisplayP3 color space (I show an image of the picker below, and you can see the "Display P3 Hex Colour" at the bottom).
If you give it a color in sRGB, I think it gets converted to DisplayP3. When you read the color, you need to convert back to sRGB, which is the step I missed.
However I found that using CGColor.CreateByMatchingToColorSpace, to convert from DisplayP3 to sRGB never quite worked. In the code below I convert to and from DisplayP3 and should have got back my original color, but I never did. I tried removing Gamma by converting to a Linear space on the way but that didn't help.
cg = new CGColor(...values...); // defaults to sRGB
// sRGB to DisplayP3
tmp = CGColor.CreateByMatchingToColorSpace(
CGColorSpace.CreateWithName("kCGColorSpaceDisplayP3"),
CGColorRenderingIntent.Default, cg, null);
// DisplayP3 to sRGB
cg2 = CGColor.CreateByMatchingToColorSpace(
CGColorSpace.CreateWithName("kCGColorSpaceExtendedSRGB"),
CGColorRenderingIntent.Default, tmp, null);
Then I found an excellent resource: http://endavid.com/index.php?entry=79 that included a set of matrices that can perform the conversions. And that seems to work.
So now I have extended CGColor as follows:
public static CGColor FromExtendedsRGBToDisplayP3(this CGColor c)
{
if (c.ColorSpace.Name != "kCGColorSpaceExtendedSRGB")
throw new Exception("Bad color space");
var mat = LinearAlgebra.Matrix<float>.Build.Dense(3, 3, new float[] { 0.8225f, 0.1774f, 0f, 0.0332f, 0.9669f, 0, 0.0171f, 0.0724f, 0.9108f });
var vect = LinearAlgebra.Vector<float>.Build.Dense(new float[] { (float)c.Components[0], (float)c.Components[1], (float)c.Components[2] });
vect = vect * mat;
var cg = new CGColor(CGColorSpace.CreateWithName("kCGColorSpaceDisplayP3"), new nfloat[] { vect[0], vect[1], vect[2], c.Components[3] });
return cg;
}
public static CGColor FromP3ToExtendedsRGB(this CGColor c)
{
if (c.ColorSpace.Name != "kCGColorSpaceDisplayP3")
throw new Exception("Bad color space");
var mat = LinearAlgebra.Matrix<float>.Build.Dense(3, 3, new float[] { 1.2249f, -0.2247f, 0f, -0.0420f, 1.0419f, 0f, -0.0197f, -0.0786f, 1.0979f });
var vect = LinearAlgebra.Vector<float>.Build.Dense(new float[] { (float)c.Components[0], (float)c.Components[1], (float)c.Components[2] });
vect = vect * mat;
var cg = new CGColor(CGColorSpace.CreateWithName("kCGColorSpaceExtendedSRGB"), new nfloat[] { vect[0], vect[1], vect[2], c.Components[3] });
return cg;
}
Note: there's lots of assumptions in the matrices w.r.t white point and gammas. But it works for me. Let me know if there are better approaches out there, or if you can tell me why my use of CGColor.CreateByMatchingToColorSpace didn't quite work.
Reading Resources:
Reading this: https://stackoverflow.com/a/49040628/6257435
then this: https://bjango.com/articles/colourmanagementgamut/
are essential starting points.
Image of the iOS Color Picker:
I am trying to convert this hash color code #159424 (GREEN-COLOR) to more darken and lighten programmatically. How to do this please help?
make green color darker
toDarkColor(String hashColor){
// how to convert that hash string to make green color darker?
}
make green color lighter
toLightColor(String hashColor){
// how to convert that hash string to make green color lighter?
}
For people who want to darken or lighten Color instead of hex string
// ranges from 0.0 to 1.0
Color darken(Color color, [double amount = .1]) {
assert(amount >= 0 && amount <= 1);
final hsl = HSLColor.fromColor(color);
final hslDark = hsl.withLightness((hsl.lightness - amount).clamp(0.0, 1.0));
return hslDark.toColor();
}
Color lighten(Color color, [double amount = .1]) {
assert(amount >= 0 && amount <= 1);
final hsl = HSLColor.fromColor(color);
final hslLight = hsl.withLightness((hsl.lightness + amount).clamp(0.0, 1.0));
return hslLight.toColor();
}
// usage
final lightRed = lighten(Colors.red);
final darkBlue = darken(Colors.blue, .3);
Live Demo
Color accurate solution with no plugin
The accepted answer changes the tint of colors when darkening (the tint is more saturated). Also its lightening function produces pure white with an amount of 0.3 for some colors although white should only be reached with an amount of 1.
The two following methods produce shades of the base color that seem 'darker' or 'lighter' without changing the tint.
import 'package:flutter/material.dart';
/// Darken a color by [percent] amount (100 = black)
// ........................................................
Color darken(Color c, [int percent = 10]) {
assert(1 <= percent && percent <= 100);
var f = 1 - percent / 100;
return Color.fromARGB(
c.alpha,
(c.red * f).round(),
(c.green * f).round(),
(c.blue * f).round()
);
}
/// Lighten a color by [percent] amount (100 = white)
// ........................................................
Color lighten(Color c, [int percent = 10]) {
assert(1 <= percent && percent <= 100);
var p = percent / 100;
return Color.fromARGB(
c.alpha,
c.red + ((255 - c.red) * p).round(),
c.green + ((255 - c.green) * p).round(),
c.blue + ((255 - c.blue) * p).round()
);
}
Example: darken a color by 15%.
final Color darkerGreen = darken(Color(0xFF159424), 15);
If starting from a Hex String value as OP asked, use J.M. Taylor' solution:
Color hexToColor(String code) {
return Color(int.parse(code.substring(0, 6), radix: 16) + 0xFF000000);
}
final Color darkerGreen = darken(hexToColor('#159424'));
Note: it's for Flutter projects as it uses the material's Color class.
My solution based on https://stackoverflow.com/a/58604669/7479173
extension ColorBrightness on Color {
Color darken([double amount = .1]) {
assert(amount >= 0 && amount <= 1);
final hsl = HSLColor.fromColor(this);
final hslDark = hsl.withLightness((hsl.lightness - amount).clamp(0.0, 1.0));
return hslDark.toColor();
}
Color lighten([double amount = .1]) {
assert(amount >= 0 && amount <= 1);
final hsl = HSLColor.fromColor(this);
final hslLight =
hsl.withLightness((hsl.lightness + amount).clamp(0.0, 1.0));
return hslLight.toColor();
}
}
with this one can simply:
Colors.red.darken()
Colors.red.lighten()
Colors.red.lighten(0.1)
this works on any colors as long as you import the extension.
You can use tinycolor package:
TinyColor.fromString("#159424").darken(10).color
Edit:
You can convert Color back to hex string like this:
String toHex(Color color) {
return "#${color.red.toRadixString(16).padLeft(2, "0")}"
"${color.green.toRadixString(16).padLeft(2, "0")}"
"${color.blue.toRadixString(16).padLeft(2, "0")}";
}
or if you want opacity/alpha:
String toHex(Color color) {
return "#${color.alpha.toRadixString(16).padLeft(2, "0")}"
"${color.red.toRadixString(16).padLeft(2, "0")}"
"${color.green.toRadixString(16).padLeft(2, "0")}"
"${color.blue.toRadixString(16).padLeft(2, "0")}";
}
I used withLightness method of HSLColor to lighten the color.
HSLColor.fromColor(Colors.red).withLightness(0.95).toColor()
Since some parts of TinyColor seem broken, and I only really needed lighten and darken, NearHuscarl's answer was perfect for me.
However, it was missing one part that was necessary to completely answer the original question, which was converting hash color code (declared as a String) to Color.
To do that, you can use this:
Color hexToColor(String code) {
return Color(int.parse(code.substring(0, 6), radix: 16) + 0xFF000000);
}
The above is not my code, but something I learned from a tutorial here.
Then just combine that with NearHuscarl's code to get the desired effect:
final Color darkerGreen = darken(hexToColor('#159424'));
One liner with built-in method:
Color.lerp(myColor, Colors.white, 0.4) // 0 = keep as is, 1 = white
I would like to create a brush for drawing on a PGraphics element with Processing. I would like past brush strokes to be visible. However, since the PGraphics element is loaded every frame, previous brush strokes disappear immediatly.
My idea was then to create PGraphics pg in setup(), make a copy of it in void(), alter the original graphic pg and update the copy at every frame. This produces a NullPointerException, most likely because pg is defined locally in setup().
This is what I have got so far:
PGraphics pg;
PFont font;
void setup (){
font = createFont("Pano Bold Kopie.otf", 600);
size(800, 800, P2D);
pg = createGraphics(800, 800, P2D);
pg.beginDraw();
pg.background(0);
pg.fill(255);
pg.textFont(font);
pg.textSize(400);
pg.pushMatrix();
pg.translate(width/2, height/2-140);
pg.textAlign(CENTER, CENTER);
pg.text("a", 0 , 0);
pg.popMatrix();
pg.endDraw();
}
void draw () {
copy(pg, 0, 0, width, height, 0, 0, width, height);
loop();
int c;
loadPixels();
for (int x=0; x<width; x++) {
for (int y=0; y<height; y++) {
pg.pixels[mouseX+mouseY*width]=0;
}
}
updatePixels();
}
My last idea, which I have not attempted to implement yet, is to append pixels which have been touched by the mouse to a list and to draw from this list each frame. But this seems quite complicated to me as it might result into super long arrays needing to be processed on top of the original image. So, I hope there is another way around!
EDIT: My goal is to create a smudge brush, hence a brush which kind of copies areas from one part of the image to other parts.
There's no need to manually copy pixels like that. The PGraphics class extends PImage, which means you can simply render it with image(pg,0,0); for example.
The other thing you could do is an old trick to fade the background: instead of clearing pixels completely you can render a sketch size slightly opaque rectangle with no stroke.
Here's a quick proof of concept based on your code:
PFont font;
PGraphics pg;
void setup (){
//font = createFont("Pano Bold Kopie.otf", 600);
font = createFont("Verdana",600);
size(800, 800, P2D);
// clear main background once
background(0);
// prep fading background
noStroke();
// black fill with 10/255 transparnecy
fill(0,10);
pg = createGraphics(800, 800, P2D);
pg.beginDraw();
// leave the PGraphics instance transparent
//pg.background(0);
pg.fill(255);
pg.textFont(font);
pg.textSize(400);
pg.pushMatrix();
pg.translate(width/2, height/2-140);
pg.textAlign(CENTER, CENTER);
pg.text("a", 0 , 0);
pg.popMatrix();
pg.endDraw();
}
void draw () {
// test with mouse pressed
if(mousePressed){
// slowly fade/clear the background by drawing a slightly opaque rectangle
rect(0,0,width,height);
}
// don't clear the background, render the PGraphics layer directly
image(pg, mouseX - pg.width / 2, mouseY - pg.height / 2);
}
If you hold the mouse pressed you can see the fade effect.
(changing transparency to 10 to a higher value with make the fade quicker)
Update To create a smudge brush you can still sample pixels and then manipulate the read colours to some degree. There are many ways to implement a smudge effect based on what you want to achieve visually.
Here's a very rough proof of concept:
PFont font;
PGraphics pg;
int pressX;
int pressY;
void setup (){
//font = createFont("Pano Bold Kopie.otf", 600);
font = createFont("Verdana",600);
size(800, 800, P2D);
// clear main background once
background(0);
// prep fading background
noStroke();
// black fill with 10/255 transparnecy
fill(0,10);
pg = createGraphics(800, 800, JAVA2D);
pg.beginDraw();
// leave the PGraphics instance transparent
//pg.background(0);
pg.fill(255);
pg.noStroke();
pg.textFont(font);
pg.textSize(400);
pg.pushMatrix();
pg.translate(width/2, height/2-140);
pg.textAlign(CENTER, CENTER);
pg.text("a", 0 , 0);
pg.popMatrix();
pg.endDraw();
}
void draw () {
image(pg,0,0);
}
void mousePressed(){
pressX = mouseX;
pressY = mouseY;
}
void mouseDragged(){
// sample the colour where mouse was pressed
color sample = pg.get(pressX,pressY);
// calculate the distance from where the "smudge" started to where it is
float distance = dist(pressX,pressY,mouseX,mouseY);
// map this distance to transparency so the further the distance the less smudge (e.g. short distance, high alpha, large distnace, small alpha)
float alpha = map(distance,0,30,255,0);
// map distance to "brush size"
float size = map(distance,0,30,30,0);
// extract r,g,b values
float r = red(sample);
float g = green(sample);
float b = blue(sample);
// set new r,g,b,a values
pg.beginDraw();
pg.fill(r,g,b,alpha);
pg.ellipse(mouseX,mouseY,size,size);
pg.endDraw();
}
As the comments mention, one idea is to sample colour on press then use the sample colour and fade it as your drag away from the source area. This shows simply reading a single pixel. You may want to experiment with sampling/reading more pixels (e.g. a rectangle or ellipse).
Additionally, the code above isn't optimised.
A few things could be sped up a bit, like reading pixels, extracting colours, calculating distance, etc.
For example:
void mouseDragged(){
// sample the colour where mouse was pressed
color sample = pg.pixels[pressX + (pressY * pg.width)];
// calculate the distance from where the "smudge" started to where it is (can use manual distance squared if this is too slow)
float distance = dist(pressX,pressY,mouseX,mouseY);
// map this distance to transparency so the further the distance the less smudge (e.g. short distance, high alpha, large distnace, small alpha)
float alpha = map(distance,0,30,255,0);
// map distance to "brush size"
float size = map(distance,0,30,30,0);
// extract r,g,b values
int r = (sample >> 16) & 0xFF; // Like red(), but faster
int g = (sample >> 8) & 0xFF;
int b = sample & 0xFF;
// set new r,g,b,a values
pg.beginDraw();
pg.fill(r,g,b,alpha);
pg.ellipse(mouseX,mouseY,size,size);
pg.endDraw();
}
The idea is to start simple with clear, readable code and only at the end, if needed look into optimisations.
When I add a semi-transparent image (sample) as a texture for a SCNNode, how can I specify a color attribute for the node where the image is transparent. Since I am able to specify either color or image as a material property, I am unable to specify the color value to the node. Is there a way to specify both color and image for the material property or is there a workaround to this problem.
If you are assigning the image to the contents of the transparent material property, you can change the materials transparencyMode to be either .AOne or .RGBZero.
.AOne means that transparency is derived from the images alpha channel.
.RGBZero means that transparency is derived from the luminance (the total red, green, and blue) in the image.
You cannot configure an arbitrary color to be treated as transparency without a custom shader.
However, from the looks of your sample image, I would think that assigning the sample image to the transparent material properties contents and using the .AOne transparency mode would give you the result you are looking for.
I'm posting this as a new answer because it's different from the other answer.
Based on your comment, I understand that you want to want to use an image with transparency as the diffuse content of a material, but use a background color wherever the image is transparent. In other words, you won't to use a composite of the image over a color as the diffuse contents.
Using UIImage
There are a few different ways you can achieve this composited image. The easiest and likely most familiar solution is to create a new UIImage that draws the image over the color. This new image will have the same size and scale as your image, but can be opaque since it has a solid background color.
func imageByComposing(image: UIImage, over color: UIColor) -> UIImage {
UIGraphicsBeginImageContextWithOptions(image.size, true, image.scale)
defer {
UIGraphicsEndImageContext()
}
let imageRect = CGRect(origin: .zero, size: image.size)
// fill with background color
color.set()
UIRectFill(imageRect)
// draw image on top
image.drawInRect(imageRect)
return UIGraphicsGetImageFromCurrentImageContext()
}
Using this image as the contents of the diffuse material property will give you the effect that you're after.
Using Shader Modifiers
If you find yourself having to change the color very frequently (possibly animating it), you could also use custom shaders or shader modifiers to composite the image over the color.
In that case, you want to composite the image A over the color B, so that the output color (CO) is:
CO = CA + CB * (1 - ɑA)
By passing the image as the diffuse contents, and assigning the output to the diffuse content, the expression can be simplified as:
Cdiffuse = Cdiffuse + Ccolor * (1 - ɑdiffuse)
Cdiffuse += Ccolor * (1 - ɑdiffuse)
Generally the output alpha would depend on the alpha of A and B, but since B (the color) is opaque (1), the output alpha is also 1.
This can be written as a small shader modifier. Since the motivation for this solutions was to be able to change the color, the color is created as a uniform variable which can be updated in code.
// Define a color that can be set/changed from code
uniform vec3 backgroundColor;
#pragma body
// Composit A (the image) over B (the color):
// output = image + color * (1-alpha_image)
float alpha = _surface.diffuse.a;
_surface.diffuse.rgb += backgroundColor * (1.0 - alpha);
// make fully opaque (since the color is fully opaque)
_surface.diffuse.a = 1.0;
This shader modifier would then be read from the file, and set in the materials shader modifier dictionary
enum ShaderLoadingError: ErrorType {
case FileNotFound, FailedToLoad
}
func shaderModifier(named shaderName: String, fileExtension: String = "glsl") throws -> String {
guard let url = NSBundle.mainBundle().URLForResource(shaderName, withExtension: fileExtension) else {
throw ShaderLoadingError.FileNotFound
}
do {
return try String(contentsOfURL: url)
} catch {
throw ShaderLoadingError.FailedToLoad
}
}
// later, in the code that configures the material ...
do {
let modifier = try shaderModifier(named: "Composit") // the name of the shader modifier file (assuming 'glsl' file extension)
theMaterial.shaderModifiers = [SCNShaderModifierEntryPointSurface: modifier]
} catch {
// Handle the error here
print(error)
}
You would then be able to change the color by setting a new value for the "backgroundColor" of the material. Note that there is no initial value, so one would have to be set.
let backgroundColor = SCNVector3Make(1.0, 0.0, 0.7) // r, g, b
// Set the color components as an SCNVector3 wrapped in an NSValue
// for the same key as the name of the uniform variable in the sahder modifier
theMaterial.setValue(NSValue(SCNVector3: backgroundColor), forKey: "backgroundColor")
As you can see, the first solution is simpler and the one I would recommend if it suits your needs. The second solution is more complicated, but enabled the background color to be animated.
Just in case someone comes across this in the future... for some tasks, ricksters solution is likely the easiest. In my case, I wanted to display a grid on top of an image that was mapped to a sphere. I originally composited the images into one and applied them, but over time I got more fancy and this started getting complex. So I made two spheres, one inside the other. I put the grid on the inner one and the image on the outer one and presto...
let outSphereGeometry = SCNSphere(radius: 20)
outSphereGeometry.segmentCount = 100
let outSphereMaterial = SCNMaterial()
outSphereMaterial.diffuse.contents = topImage
outSphereMaterial.isDoubleSided = true
outSphereGeometry.materials = [outSphereMaterial]
outSphere = SCNNode(geometry: outSphereGeometry)
outSphere.position = SCNVector3(x: 0, y: 0, z: 0)
let sphereGeometry = SCNSphere(radius: 10)
sphereGeometry.segmentCount = 100
sphereMaterial.diffuse.contents = gridImage
sphereMaterial.isDoubleSided = true
sphereGeometry.materials = [sphereMaterial]
sphere = SCNNode(geometry: sphereGeometry)
sphere.position = SCNVector3(x: 0, y: 0, z: 0)
I was surprised that I didn't need to set sphereMaterial.transparency, it seems to get this automatically.
I am using Starling.
I can't figure out how to make alpha part of bitmap non-clickable - say I have a rabbit in center and alpha around.
first i embed the bitmap:
[Embed(source="assets/stuff.xml", mimeType="application/octet-stream")]public static const Axml:Class;
[Embed(source="assets/stuff.png")]public static const Apng:Class;
Then create the bitmap atlass (spritesheet):
var tx1:Texture = Texture.fromBitmap(new Apng());
var xm1:XML = XML(new Axml());
var atlas:TextureAtlas = new TextureAtlas(tx1, xm1);
I made a MovieClip and add bitmap to it like that:
var movie:MovieClip = new MovieClip(atlas.getTextures("rabbit_run_"), 18);
addChild(movie);
movie.play();
starling.core.Starling.juggler.add(movie);
but when I click on it even on alpha part movieClip becomes "clicked".
I only need rabbit itself to be clickable, not around it!
How to make alpha non-clickable? Thanks
1: You cannot make image clickable in one area and nonclickable in another. But you can get color of pixel under mouse and ignore ckicks over transparent pixels
import flash.events.MouseEvent;
import flash.display.BitmapData;
var rabbitBitmap:BitmapData = new BitmapData(rabbit.width, rabbit.height, true, 0xFFFFFFFF);
rabbitBitmap.draw(rabbit);
addEventListener(MouseEvent.MOUSE_MOVE, mmh)
rabbit.addEventListener(MouseEvent.CLICK, mch)
rabbit.buttonMode = true;
function mmh(e:MouseEvent):void {
rabbit.useHandCursor = getAlpha() != 255;
}
function mch(e:MouseEvent):void {
if (getAlpha() != 255) {
// ... do someth
}
}
function getAlpha ():int {
var rgba:uint = rabbitBitmap.getPixel32(rabbit.mouseX, rabbit.mouseY);
return rgba & 0xff;
}
2: Use vector graphics for your rabbit :)