Re: [webkit-dev] FontPlatformData, FontCache and HashMap
I have a related question about SimpleFontData and FontPlatformData.
When does Webkit create a FontPlatformData and SimpleFontData?
I too put debug printfs in these classes constructors. And I see
Webkit creates different FontPlatformData and SimpleFontData for same
font family and same font size.
Thank you for any tip in helping me understanding.
On Thu, Feb 18, 2010 at 12:28 PM, Stephan Assmus supersti...@gmx.de wrote:
On 2010-02-18 at 18:43:08 [+0100], Stephan Assmus supersti...@gmx.de wrote:
Hi all,
currently, I am investigating some weirdness with regards to
FontPlatformData and the FontCache which I see in my debugging output on
the Haiku port. I am not even 100% sure that what I see is a weirdness, but
at least I don't understand it and I was wondering if anyone could help me
shed some light into this.
So I understand these things:
1) SimpleFontData has a member m_platformData of type FontPlatformData,
which is always instantiated by passing it a const reference of another
FontPlatformData.
2) The FontCache maintains SimplaFontData instances in a HashMap, and looks
these up and compares them by using FontPlatformData objects as keys into
the map.
3) FontCache has a static empty FontPlatformData instance in
FontDataCacheKeyTraits:
static const FontPlatformData emptyValue()
{
DEFINE_STATIC_LOCAL(FontPlatformData, key, (0.f, false, false));
return key;
}
Don't yet know how this comes into play, but possibly it's of relevance.
My analysis is a bit awkward, since I cannot use a source level debugger on
Haiku, and I won't bore you with the embarrasing details of why. So I added
printf() statements in all my constructors of FontPlatformData, and printed
among other things the memory address of the FontPlatformData instance
(this). Also, I am printing this in a number of other places, operator=()
for example. The output I am getting is a little weird, since it shows that
operator=() is called on objects, for which no constructor has been called.
Basically, I've narrowed it down to SimpleFontData*
FontCache::getCachedFontData(const FontPlatformData* platformData) in
FontCache.cpp. In this method, a new SimpleFontData instance is to be
created and inserted into the HashMap. I will show you the output from the
program start. It printed which FontPlatformData instances have been
created up to Kill Thread (I let it drop into the debugger from the first
invokation of FontPlatformData::operator=()):
The first font is created:
getCachedFontPlatformData(0)
createFontPlatformData(const FontDescription)
0x18018660-FontPlatformData(const FontDescription(16.0, Myriad Pro))
0x18019bf0-FontPlatformDataPrivate()
created result: 0x18018660
getCachedFontPlatformData() - done: 0x18018660
Next, getCachedFontData() is called to insert a new SimpleFontData for this
FontDescription:
getCachedFontData(0x18018660)
Next comes the output from line 289 of FontCache.cpp:
pairSimpleFontData*, unsigned newValue(new SimpleFontData(*platformData),
1);
A new SimpleFontData object is created with it's m_fontData member at
address 0x2f4c6a8:
0x2f4c6a8-FontPlatformData(const FontPlatformData 0x18018660)
0x18019bf0-addRef()
new: 0x2f4c680
Next comes the call to HashMap::set(), which results in this output:
0x18018970-FontPlatformData(0.0, 0, 0)
This is probably the key created from HashMap::inlineAdd(). And next,
HashMap::set() invokes operator=() on the key (line 250) which gives this
output:
0x2ec8594 ((nil), 0.0, 0, 0) -operator=(0x18018660, 0x18019bf0)
nil is a pointer to FontPlatformDataPrivate, which is ok. But 0x2ec8594
should be the pointer to the FontPlatformData instance created in
inlineAdd().
How can I be doing something wrong there? Nothing happens in my constructor
for FontPlatformData() when the empty key values are used. Maybe the usage
of the HashMap is broken in FontCache, since it would seem that such a
low-level utility class as HashMap would not likely contain any bugs.
Ok, I've finally figured it out. FontCache.cpp defines the following for use
in the HashMap:
struct FontDataCacheKeyTraits : WTF::GenericHashTraitsFontPlatformData {
static const bool emptyValueIsZero = true;
static const bool needsDestruction = true;
static const FontPlatformData emptyValue()
{
DEFINE_STATIC_LOCAL(FontPlatformData, key, (0.f, false, false));
return key;
}
static void constructDeletedValue(FontPlatformData slot)
{
new (slot) FontPlatformData(HashTableDeletedValue);
}
static bool isDeletedValue(const FontPlatformData value)
{
return value.isHashTableDeletedValue();
}
};
The emptyValueIsZero means the HashTable implementation will not call
constructors for new slots. IMHO, this is a dangerous assumption, since the
porters may not realize this and that this actually works is completely
implementation specific.
Best
[webkit-dev] RenderContainer class in webkit source code
Hi, Can you please tell me if the RenderContainer class in webkit source code got removed? I notice this class in android's webkit source, but when I check the code in webkit trunk, that class is not there. Can you please if that class got removed? Thank you ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
Re: [webkit-dev] RenderContainer class in webkit source code
Thanks. I am not sure how to use ChangeLogs. On Fri, Jul 3, 2009 at 5:58 PM, Simon Frasersimon.fra...@apple.com wrote: On Jul 3, 2009, at 5:41 PM, n179911 wrote: Hi, Can you please tell me if the RenderContainer class in webkit source code got removed? I notice this class in android's webkit source, but when I check the code in webkit trunk, that class is not there. Can you please if that class got removed? Thank you Use those ChangeLogs that you've heard so much about. They show that RenderContainer was eliminated on 2009-02-04. Simon ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
[webkit-dev] WebKit graphics library abstract layer
Webkit supports on multiple platform (e.g. Windows, MacOS, linux). And when Webkit paints content on screen, it needs to call native graphics api to paint (e.g. draw text, draw image, draw line, draw rect). Does Webkit code has an abstract layer, which hides the platform dependent graphics API. And the render engine just calls this abstract layer graphics api and this abstract layer api will handle, or link in platform dependent implementation of those draw text, draw rect calls? If yes, can you least tell me where can I find this abstract layer code. Thank you. ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
[webkit-dev] Dimension of Render Containers
Hi,
Does the dimension (width X height) of Render Containers (e.g.
RenderBlock, RenderTableRow, RenderTableCell) always encompass all its
children?
For example,
The Render Block is 145 x 14 which encompasses its children
RenderInline (145x12), RenderText (145x12)
RenderBlock (floating) {DIV} at (458,5) size 145x14 [color=#CC]
{467.00,212.00}
RenderInline {A} at (0,0) size 145x12 [color=#004276]
{467.00,212.00}
RenderText {#text} at (0,1) size 145x12 {467.00,212.00}
text run at (0,1) width 145: Make CNN Your Home Page
Is this always the case? Or there are exceptions to such rule?
e.g. nested DIV Tags, does the outermost DIV Tag encompasses the inner
one and and the inner one encompasses the one inside it?
Thank you.
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Re: [webkit-dev] Dimension of Render Containers
On Thu, Jun 25, 2009 at 9:50 AM, n179911n179...@gmail.com wrote:
Hi,
Does the dimension (width X height) of Render Containers (e.g.
RenderBlock, RenderTableRow, RenderTableCell) always encompass all its
children?
For example,
The Render Block is 145 x 14 which encompasses its children
RenderInline (145x12), RenderText (145x12)
RenderBlock (floating) {DIV} at (458,5) size 145x14 [color=#CC]
{467.00,212.00}
RenderInline {A} at (0,0) size 145x12 [color=#004276]
{467.00,212.00}
RenderText {#text} at (0,1) size 145x12 {467.00,212.00}
text run at (0,1) width 145: Make CNN Your Home
Page
Is this always the case? Or there are exceptions to such rule?
e.g. nested DIV Tags, does the outermost DIV Tag encompasses the inner
one and and the inner one encompasses the one inside it?
Thank you.
I found a case which does not follow this rule (The Render container
encompasses its children dimension:
RenderBlock (anonymous) at (2,0) size 980x0 {11.00,147.00}
RenderInline {A} at (0,0) size 0x0
[color=#004276] {11.00,147.00}
RenderImage {IMG} at (956,0) size 24x27 {967.00,147.00}
The container is 980x0, but it has a child 24x27.
Not sure if the RenderBlock is 'anonymous' (like in this case) means
it break such rule.
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[webkit-dev] Tab key Navigation
Hi, Is 'Tab key Navigation a browser functionality or Webkit functionally? For example, I load google.com, I put my mouse on the search input box click once. The search input box should have focus. And then i press 'Tab', the focus should moved. But what I find out is the way Safari moves focus is different from Chromium (both uses Webkit but may be using different versions). So I would like to know if the Tab key navigation a Webkit functionality or a Browser functionality? Thank you., ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
