Robin Dijkhof :
I'm rebuilding my app from java to flutter. I'm using firebase to store colors as integer values. In java I can use the following to convert rgb values to integer values:
colorInt = (255 << 24) | (color.red << 16) | (color.green << 8) | color.blue;
And I can use the following to convert from an integer value to rgb:
int r = (colorInt >> 16) & 0xFF;
int g = (colorInt >> 8) & 0xFF;
int b = colorInt & 0xFF;
How can I convert a Java integercolor to a flutter color and back?
An example, lets take RGB 154, 255, 147
In flutter this would be the result is 4288348051
(255 << 24) | (154 << 16) | (255 << 8) | 147;
(4278190080) | (10092544) | (65280) | 147;
(4278190080) | (10092544) = 4288282624;
(4278190080) | (10092544) | (65280) = 4288347904;
(4278190080) | (10092544) | (65280) | 147 = 4288348051
In java this would be -6619245
(255 << 24) | (154 << 16) | (255 << 8) | 147;
(-16777216) | (10092544) | (65280) | 147;
(-16777216) | (10092544) = -6684672;
(-16777216) | (10092544) | (65280) = -6619392;
(-16777216) | (10092544) | (65280) | 147 = -6619245;
AKushWarrior :
So, as @Ovidiu mentioned, Java uses signed 32 bit integers. Expanding on the code block they posted, we can create a full example which gives us what we need:
import 'dart:math';
int chopToJavaInt (int result) {
while (result > pow(2, 31)) {
result = result - pow(2, 32);
}
return result;
}
int javaIntColor(int r, int g, int b) {
var x = (g << 24) | (r << 16) | (g << 8) | b;
return chopToJavaInt(x);
}
void main () {
print(javaIntColor(154, 255, 147)); //-6619245
}
This solution is modular, maintains your original style from your Java code, and will return the correct value.
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