Exception calling Canvas2DRenderingContext.setFillColor

[DartBot]

This issue was originally filed by [email protected]

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The following code fails:

   CanvasElement canvas = ...;
   CanvasRenderingContext2D ctx = canvas.getContext("2d");
   ctx.setFillColor("#ffffff");

It also fails if "#ffffff" is replaced with 0xffffff.

The browser reports the error:

Uncaught TypeError: Object #ffffff has no method 'ptr$html623afa$$getter'

The offending stack looks like:

html623afa$LevelDom$Dart.unwrap$memberTotal.dart.app.js:181736
html623afa$CanvasRenderingContext2DWrappingImplementation$Dart.setFillColor$memberTotal.dart.app.js:186089
html623afa$CanvasRenderingContext2DWrappingImplementation$Dart.setFillColor$namedTotal.dart.app.js:186158
TotalLib58392f$ClientLineChart$Dart.render$member

It seems that the html library is attempting to unwrap an unwrapped parameter.

[DartBot]

This comment was originally written by [email protected]

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Added Area-UI, Triaged labels.

[dgrove]

Set owner to @jacob314.

[DartBot]

This comment was originally written by [email protected]

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I saw the same problem when I use
#import('dart:html');
#import('dart:dom');
or
#import('dart:html');

If I use only
#import('dart:dom');
it works.

[justinfagnani]

I just ran into the same problem using canvas in dart:html. Same problem with setStrokeColor()

A guess about the problem:

Not knowing how the libraries and compiler work, I do notice that LevelDom.unwrap is being called on what is known to be a String argument when invoking the wrapped method, but in other locations in the library Strings are not unwrapped.

_CanvasRenderingContext2DWrappingImplementation.dart:427
c_OR_color_OR_grayLevel_OR_r is a String:

_ptr.setFillColor(LevelDom.unwrap(c_OR_color_OR_grayLevel_OR_r));

a little further down:

void setLineCap(String cap) {
  _ptr.setLineCap(cap);
  return;
}

setLineCap() works.

[DartBot]

This comment was originally written by [email protected]

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Also setStrokeStyle and setStrokeColor are not working.

[DartBot]

This comment was originally written by [email protected]

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The same fix works for all the above problems.

Basically LevelDom.unwrap(x)--which is hidden in the HTMLImplementation.dart if you want to see it-- is trying to access a pointer to the input. That pointer doesn't exist in non-DOM objects, such as the string we pass in, or the optional num you can pass in.

Just as J justinfagnani said, if you remove the unwrap from most of the implementations in the contextrendering2d class, then it starts working.

This works for setStrokeColor as well.

[DartBot]

This comment was originally written by [email protected]

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Issue #722 has been merged into this issue.

[DartBot]

This comment was originally written by [email protected]

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Should this be a library issue rather than a UI issue?

[jacob314]

Fixed with the latest version of dart:html

LevelDom.unwrapMaybePrimitive is used to avoid the bug.

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Added Fixed label.