Show alt text when source image is missing or broken or not found.

Show alt text when source image is missing or broken or not found.

Instead of broken image alt text needs to be displayed if its present.

This behavior is same as firefox.

BUG=157207, 773

[shreeramk, 2014-07-24 13:54:28]

Many of the layout tests will be failed as there is change in alt attribute
behavior.
The reason of layout test getting failed is because layout test cases were
written keeping broken image into picture when alt text is still present. But
mine changes will show alt text if alt attribute is present in the <img> tag and
images is missing/broken/not found.

I'll update layout test cases once it ll be reviewed that the changes done by me
are correct.

Thanks!!!

[tkent, 2014-07-24 23:41:12]

a duplication of https://codereview.chromium.org/328703003/ ?

[shreeramk, 2014-07-25 05:02:06]

On 2014/07/24 23:41:12, tkent wrote:
> a duplication of https://codereview.chromium.org/328703003/ ?

No, its not a duplication.

I am submitting this changes for two bugs 
1. Issue 157207: Img alt attribute ("alt tag") not shown if too long
2. Issue 773: Broken/missing/not found images should display ALT text

Changes submitted by me, work for both the bugs with minimal change in code. 

https://codereview.chromium.org/328703003/  - This revision only handles the
case of showing alt text, when its small. 
This revision doesn't handle following cases
1. When alt text is long - (Result - Broken image will be seen)
2. When width is specified for the <img> & alt text width is more than the width
specified for the <img>
(Hence in both of the above unhandled cases broken image will be seen, if alt
text is present with mentioned conditions in point 1 and 2)

[esprehn, 2014-08-01 13:45:25]

https://codereview.chromium.org/419453003/diff/40001/Source/core/rendering/Re...
File Source/core/rendering/RenderImage.cpp (right):

https://codereview.chromium.org/419453003/diff/40001/Source/core/rendering/Re...
Source/core/rendering/RenderImage.cpp:337: context->drawBidiText(font,
textRunPaintInfo, textOrigin);
This won't wrap the text, so I think you're just going to paint off the side of
this box which I suspect is bad since we won't invalidate properly out there.
Can you upload some baselines of what happens when there's long text that didn't
fit before?

[shreeramk, 2014-08-02 16:24:47]

On 2014/08/01 13:45:25, esprehn wrote:
>
https://codereview.chromium.org/419453003/diff/40001/Source/core/rendering/Re...
> File Source/core/rendering/RenderImage.cpp (right):
> 
>
https://codereview.chromium.org/419453003/diff/40001/Source/core/rendering/Re...
> Source/core/rendering/RenderImage.cpp:337: context->drawBidiText(font,
> textRunPaintInfo, textOrigin);
> This won't wrap the text, so I think you're just going to paint off the side
of
> this box which I suspect is bad since we won't invalidate properly out there.
> Can you upload some baselines of what happens when there's long text that
didn't
> fit before?

@esprehn:

Following scenarios:

1. <img src="missing.jpg" alt="Image is missing" > and 
Before: Broken image is shown. Why? Because alt text width is less than that of
the broken image.
After revision: alt text is shown.

2. <img src="missing.jpg" width=50px alt="Image is missing">
Before: Broken image was shown. Why? Because alt text width is less than
specified width for the <img>.
After: alt text is shown.

3. <img src="missing.jpg" width=150px alt="Image is missing">
Before: Broken image and alt text both are shown.
After: It will show only alt Text, which is correct behaviour.

4. <img src="missing.jpg" width=1024px alt="Image is missing and some long alt
text more than 1024px Image is missing and some long alt text more than 1024px
Image is missing and some long alt text more than 1024px">

Before: Broken Image is shown. WHY? Because alt text width is more than the
specified width(1024px) for the <img>.
After: alt text is shown.


And yes I think my revision won't wrap the alt text. And also without my
revision there was no wrap of alt text.
In case of long alt text it will paint off the side of the box only if width is
specified for <img> and its less than the alt text width.

[esprehn, 2014-08-13 06:01:08]

On 2014/08/02 at 16:24:47, shreeram.k wrote:
> ...
> 
> And yes I think my revision won't wrap the alt text. And also without my
revision there was no wrap of alt text.
> In case of long alt text it will paint off the side of the box only if width
is specified for <img> and its less than the alt text width.

What invalidates the overflow from the alt text? I don't think your change works
properly since you end up drawing text outside the bounds of your box without
having real overflow.

You also need to add new tests for each of the cases you described and the
dynamic alt text one I describe.

[shreeramk, 2014-08-13 06:14:30]

On 2014/08/13 06:01:08, esprehn wrote:
> On 2014/08/02 at 16:24:47, shreeram.k wrote:
> > ...
> > 
> > And yes I think my revision won't wrap the alt text. And also without my
> revision there was no wrap of alt text.
> > In case of long alt text it will paint off the side of the box only if width
> is specified for <img> and its less than the alt text width.
> 
> What invalidates the overflow from the alt text? I don't think your change
works
> properly since you end up drawing text outside the bounds of your box without
> having real overflow.

If width is not specified and alt text is long, in that case there will be no
overflow, box will be drawn around the long alt text.

But if width is specified for <img> and alt text width is longer than the width
specified, in that scenario it will overflow the box and will be painted outside
the box also.

Since content creator has specified a long alt text with a width for <img> tag,
then if invalidation is done, then what to be shown, broken image or ... ??


> You also need to add new tests for each of the cases you described and the
> dynamic alt text one I describe.

Ok. I ll add the test cases which I described.

[shreeramk, 2014-08-20 07:03:42]

@espreh 
PTAL.

Regarding Invalidating alt text.

Case 1: If no width is specified and alt text is present, then when should we
invalidate?
Refer - image-alt-text-no-width-expected.png 

Case 2: If width(say 50px) is specified and alt Text width is more, then should
we only show alt text till the box boundary of <img> tag?
Refer - image-alt-text-width-expected.png

[esprehn, 2014-08-21 06:48:17]

On 2014/08/20 at 07:03:42, shreeram.k wrote:
> @espreh 
> PTAL.
> 
> Regarding Invalidating alt text.
> 
> Case 1: If no width is specified and alt text is present, then when should we
invalidate?
> Refer - image-alt-text-no-width-expected.png 
> 
> Case 2: If width(say 50px) is specified and alt Text width is more, then
should we only show alt text till the box boundary of <img> tag?
> Refer - image-alt-text-width-expected.png

I don't think this can work, you'd need to issue an invalidation based on the
size of the text when something changes since you're drawing outside the bounds
of the box and not maintaining overflow. We probably shouldn't show the alt text
if it doesn't fit and wait for https://codereview.chromium.org/481753002

You might also try talking to rhogan.