use Color Class in GWT

Question

I want to use Color ,in my GWT client side ,

i want this kind of color

                 public static Color myColor = new Color( 152, 207, 204) ;

if i use this import

                    import java.awt.Color;

at Client side it gives me error:

             No source code is available for type java.awt.Color; did you forget to inherit a required module

How can i use RGB colors in GWT client side , by NOT using CSS.

A1exandr Belan · Accepted Answer · 2013-03-18T11:36:56.707

You can write a simple RGB-to-String converter:

public final  class Helper {
    public static String RgbToHex(int r, int g, int b){
      StringBuilder sb = new StringBuilder();
      sb.append('#')
      .append(Integer.toHexString(r))
      .append(Integer.toHexString(g))
      .append(Integer.toHexString(b));
      return sb.toString();
    }
}

And use it:

nameField.getElement().getStyle().setBackgroundColor(Helper.RgbToHex(50, 100, 150));

---Update---

More complex way with controlling of negative value, great than 255, and 0-15 value.

  public static String RgbToHex(int r, int g, int b){
    StringBuilder sb = new StringBuilder();
    sb.append('#')
    .append(intTo2BytesStr(r))
    .append(intTo2BytesStr(g))
    .append(intTo2BytesStr(b));
    return sb.toString();
  }

  private static String intTo2BytesStr(int i) {
    return pad(Integer.toHexString(intTo2Bytes(i)));
  }

  private static int intTo2Bytes(int i){
    return (i < 0) ? 0 : (i > 255) ? 255 : i;
  }

  private static String pad(String str){
    StringBuilder sb = new StringBuilder(str);
    if (sb.length()<2){
      sb.insert(0, '0');
    }
    return sb.toString();
  }

I don't think this is going to work well for R/G/B values below 16 decimal (10 hex) ... for example, (5, 10, 20) will result in a string that contains "#5a14" ... not what you want! — Andy King, Mar 18 '13 at 04:45
@Andy King You right. But here is some other problems: 1. Negative value of int. 2. Value > than 255. — A1exandr Belan, Mar 18 '13 at 08:27
@FFire - Sure, you can add checks for invalid values; I was just pointing out that **valid** values were not all handled correctly. (btw, I'd recommend that, if you're going to use a `StringBuilder`, you should pass the one object around among your helper routines, instead of creating four `StringBuilder` instances every time the `RgbToHex` method is invoked). — Andy King, Mar 19 '13 at 01:14

score 2 · Answer 2 · answered Mar 14 '13 at 07:36

2

You are using AWT class of Color.

GWT != Java .  //so gwt compiler wont compile the awt classes

Use this ThirdParty Color Class instead.

Just copy that class into your utility package and use it on client side.

answered Mar 14 '13 at 07:36

Suresh Atta

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thanks , actually i am using it in CellTable with extended rows , So i was previously using this for making my columns color: td.style().trustedBackgroundColor("blue"); :: Now its not taking anything except String , Any way i can give these RGB colors to my celltable Cell. – junaidp Mar 14 '13 at 07:44
May be the method takes only w3c slandered colors ..here is the list of standered colrs http://www.docsteve.com/DocSteve/TechNotes/color_test.html. – Suresh Atta Mar 14 '13 at 07:51
thanks , +1 for this list , it will be helpful , but ideally to have some way to put the RGB colors of my own – junaidp Mar 14 '13 at 07:54
have you tried with the getHexValue() method in the class which i gave ??it will return the color code like "#000000" then you can pass i think. – Suresh Atta Mar 14 '13 at 07:57

score 0 · Answer 3 · answered Mar 14 '13 at 07:48

0

You used awt api color here. but GWT does not emulate this library. Refer:

JRE Emulation Reference

answered Mar 14 '13 at 07:48

bNd

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score 0 · Answer 4 · answered Mar 18 '13 at 04:54

Here's a more correct version of the RgbToHex method from the answer by FFire (this version will work correctly for r/g/b values less than 16):

public static String rgbToHex(final int r, final int g, final int b) {
  return "#" + (r < 16 ? "0" : "") + Integer.toHexString(r) + (g < 16 ? "0" : "") +
         Integer.toHexString(g) + (b < 16 ? "0" : "") + Integer.toHexString(b);
}

Of course, you can use a StringBuilder if you wish.

use Color Class in GWT

4 Answers4

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