Smalltalk/X Webserver

Documentation of class 'HTMLDocumentPainter':

Class: HTMLDocumentPainter

Inheritance
Description
Class protocol
Instance protocol
Private classes

Inheritance:

   Object
   |
   +--HTMLDocumentInterpreter
      |
      +--HTMLDocumentPainter

Package:: stx:libhtml

Category:: System-Documentation

Version:: rev: 1.424 date: 2023/10/05 09:25:21; user: stefan; file: HTMLDocumentPainter.st directory: libhtml; module: stx stc-classLibrary: libhtml

Description:

Before you use this, read the caveat below.

This one is responsible to paint a document (a linked list
of HTMLElements) into some drawable.

The major entry points are:
format:for:resolver:style:
to scan the list for applets, widgets
and preformat it.

reformatDocument
to reformat the document after a size change of the
drawable.

displayX:y:width:height:on:
to redraw (part of) the document.

Caveat:
This was written at a time when machines with 4M of main memory were
considered as ''big machines''. So the code tries hard to save memory,
in order to be able to display big documents on such small machines reasonably fast.

This is done by avoiding an in-memory html dom-tree, but instead reparsing the
document for redraws, and repeating the layout computations every time we draw.

Of course, in order to figure out what to draw when positioning (scrolling),
we would have to redo all calculations from the start of the document.
(i.e. parse the whole document for every redraw).
Which would be a stupid idea, making the thing super slow.
Therefore, it saves so called sync-points, which contain the captured state
(x, y position, font, position in document etc.) after every few pages worth
of text.
So, to update any random page, it has to search for the last sync-point
before that page, and rerender (parse) from there till the end of the visible page.
The way to get the state for a sync point is cheap and simple: a shallow copy of myself.

This scheme worked quite well for simple documents in those small-memory systems,
but it is complicated, error prone, and has problems with more complex documents
(involving style, box models, complex tables etc.).
So now, as we have gigabytes of memory, noone would do it that way.
Meaning:
it ought to be rewritten, to implement a proper dom tree, and the drawing
engine to implement a proper box model.

However:
we are not going into the browser business here
and there is no return of investment if we tried.

The HTMPainter was written for, and should only be used to display simple help texts,
online documentation and html tooltips.
It will also not be enhanced and maintained, except for obvious bugs which
break rendering the above mentioned use cases.

Anyone in need for such a thing should investigate better renderers
(which exist - both written in Smalltalk and as plugins,
using common rendering engines or embedded frameworks like CEF).

[pending bugs:]
these should be fixed, to make the documentation viewing nicer.
- <nobr> must collect text and determine if a break should be done at the beginning
- <pre>...</pre> inserts an extra empty line
- <table> is almost useless
- <img> surrounding text on the same textline must be rendered on the
baseline of the image;
currently, text after the image is shifted down

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice. This software may not
be provided or otherwise made available to, or used by, any
other person. No title to or ownership of the software is
hereby transferred.

Class protocol:

contents

headerAsString: anArray depht: depth: ** This is an obsolete interface - do not use it (it may vanish in future versions) **
headerAsString: anArray depth: depth: returns printable header assigned to array

helpers

fontFor: aFont onDevice: aDevice

romanStringFor: aNumber

aNumber >= 100 ifTrue:[

Usage example(s):

^ 'C' , (self romanStringFor:aNumber - 100)

Usage example(s):

^ 'L' , (self romanStringFor:aNumber - 50)

Usage example(s):

^ 'X' , (self romanStringFor:aNumber - 10)

Usage example(s):

^ 'V' , (self romanStringFor:aNumber - 5)

Usage example(s):

^ 'I' , (self romanStringFor:aNumber - 1)

Usage example(s):

     HTMLDocumentPainter new romanStringFor:110  
     HTMLDocumentPainter new romanStringFor:99  
     HTMLDocumentPainter new romanStringFor:9   
     HTMLDocumentPainter new romanStringFor:4    
     HTMLDocumentPainter new romanStringFor:5

image specs

bullet1

This resource specification was automatically generated
by the ImageEditor of ST/X.

Usage example(s):

     self bullet1 inspect
     ImageEditor openOnClass:self andSelector:#bullet1
     Icon flushCachedIcons

bullet2

This resource specification was automatically generated
by the ImageEditor of ST/X.

Usage example(s):

     self bullet2 inspect
     ImageEditor openOnClass:self andSelector:#bullet2
     Icon flushCachedIcons

bullet3

This resource specification was automatically generated
by the ImageEditor of ST/X.

Usage example(s):

     self bullet3 inspect
     ImageEditor openOnClass:self andSelector:#bullet3
     Icon flushCachedIcons

bullet4

This resource specification was automatically generated
by the ImageEditor of ST/X.

Usage example(s):

     self bullet4 inspect
     ImageEditor openOnClass:self andSelector:#bullet4
     Icon flushCachedIcons

bullet5

This resource specification was automatically generated
by the ImageEditor of ST/X.

Usage example(s):

     self bullet5 inspect
     ImageEditor openOnClass:self andSelector:#bullet5
     Icon flushCachedIcons

bullet6

This resource specification was automatically generated
by the ImageEditor of ST/X.

Usage example(s):

     self bullet6 inspect
     ImageEditor openOnClass:self andSelector:#bullet6
     Icon flushCachedIcons

bullet7

This resource specification was automatically generated
by the ImageEditor of ST/X.

bullet8

This resource specification was automatically generated
by the ImageEditor of ST/X.

Usage example(s):

     self bullet8 inspect
     ImageEditor openOnClass:self andSelector:#bullet8
     Icon flushCachedIcons

initialization

initialize: self initialize

instance creation

new: return an initialized instance

Instance protocol:

accessing

applets: return a collection of my applets
arrayOfHeaderIndex: returns current header index
forms: return a collection of my forms
imageResolver: somethingProvidingImagesGivenURL: Modified (format): / 29-06-2018 / 16:35:32 / Claus Gittinger
leftMargin
leftMargin: something
listOfHeaders: returns current list of headers
rightMargin
rightMargin: something
scriptObject: return my scriptObject - if any
topMargin
topMargin: something

accessing-private

currentBGColor
currentColIndex
currentColor
currentElement
currentFont
currentFontAscent
currentFontAvgHeight
currentFontHeight
currentForm
currentIndentOffset
currentLeftIndent
currentRightIndent
currentRowIndex
currentTable
currentUnderlineColor
document: aDocument
hBegin
haveSpace
inBLOCKQUOTE: returns an integer>0 if inside <blockquote>...</blockquote>
inCenter
inDL: returns an integer>0 if inside <dl>...</dl>
inKbd
inNoBreak
inOL: returns an integer>0 if inside <ol>...</ol>
inPre
inRightAlign
inStrikeout
inStyle: returns true if inside <style>...</style>
inSup
inUnderline
needSpace
previousIsEmpty
styleStack
ulLevel
xPosition
yNextLine
yPosition
yText

applets

createAppletFor: element: create the applet
defineAppletParameterFor: element: add it to its environment information
destroyApplet: appletElement
setupAppletElement: element: already present.

checking

checkInitialStateAtEndOfDocument: check for correct closing TAGS.
Although, most HTML viewers can handle this case, its usually an
indication of some error and often leads to badly formatted documents
printCheckInfoMessage: msg

contents

contentsAddHeader: text: assign text to header and store in list of headers
printContents: print contents pages
printContents: aList pageNumber: initialPageNumber romanPageNumbers: romanPageNumbers: print contents to destination

displaying

displayX: xLeft y: yTop width: w height: h on: aGC: self conditionalBreak.
pageBreak: (y > self pageBreakLimit and:[self atLeft and:[destination isView not]]) ifTrue:[
pageBreakLimit
redrawDocument: find a synchronization point

elements-document

body: why not self imageFor:bg now:true. ?
bodyEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
head: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
headEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
htmlEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
meta: already handled in parser ...
style
styleEnd: TODO: extract info
title: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
titleEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

elements-forms

anyFormElement: element
form: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
formEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
input: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
prescanForm: aFormElement: prescan a form, for its widgets max height.
a kludge - we need the form elements' heights BEFORE
formatting (since the text-elements have no origin knowledge,
which could be backpatched (also, we needed a way to break
MarkupText into multiple individual text items
prescanForms: a kludge - we need the form elements' heights BEFORE
formatting - since the text-elements have no origin knowledge,
which could be backpatched (also, we needed a way to break
MarkupText into multiple individual text items)
textarea: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
textareaEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

elements-lists

blockquote

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

blockquoteEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

dd

self conditionalBreak.

dir

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

dirEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

dl

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

dlEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

dt

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

li

this will ignore a followup BR or P

li_ol

this will ignore a followup BR or P

li_ul

in <ul> ... </ul> - draw a bullet

listTypeOElement: anElement

** This is an obsolete interface - do not use it (it may vanish in future versions) **

listTypeOfElement: anElement

menu

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

menuEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

ol

need to pass this info to </OL> element, for this to work

olEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

ul

need to pass this info to </UL> element, for this to work

Usage example(s):

indent := element numericParameterFor:'INDENT' default:ULindent.

ulEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

elements-pseudo tags

internalMathFont: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
internalMathFontEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

elements-special

a

needSpace := true.

Usage example(s):

haveSpace := true.

aEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

app

backward compatible (now obsolete) applet tag

appEnd

backward compatible (now obsolete) applet end-tag

applet

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

appletEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

area

self halt.

imageFor: urlString now: now

now:true.

img

map

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

mapEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

param

done in preparse - see #defineAppletParameterFor: ...

script

the script is now loaded and evaluated by the parser
(to allow it to generate the HTML text ...)
However, we need to remember it, for startup & cleanup message
sends.

specialMarkup

called for text

elements-structure

br

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

center

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

centerEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

div

w := element numericParameterFor:#'WIDTH' default:nil.

headline level1

headline end

headline level2

headline end

headline

headline end

headline

headline end

headline

headline end

headline

headline end

headline

headline end

headline

headline end

headline

headline end

should come from a config or classVar

nobr

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

nobrEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

p

cg: no, a P is a P

Usage example(s):

self empty.

pEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

pre

conditionalHalfEmpty.

preEnd

if the last element was a newLine, remove it

span

<span style="padding: 0 2px;border: 1px solid black;border-radius: 3px;">Connect</span>

spanEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

tab

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

wbr

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

xmp

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

xmpEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

elements-style

acronym: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
acronymEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
address: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
addressEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
b: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
bEnd: inPre ~~ 0 ifTrue:[
cite: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
citeEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
code: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
codeEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
dfn: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
dfnEnd: self handlePendingSpaceNeed.
em: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
emEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
font: a font element can also specifies bgColor, color etc.
fontEnd: inPre ~~ 0 ifTrue:[
i: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
iEnd: inPre ~~ 0 ifTrue:[
kbd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
kbdEnd: inPre ~~ 0 ifTrue:[
s: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
sEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
samp: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
sampEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
small: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
smallEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
strike: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
strikeEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
strong: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
strongEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
sub: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
subEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
sup: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
supEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
tt: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
ttEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
u: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
uEnd: self handlePendingSpaceNeed.
var: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)
varEnd: (comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

elements-tables

caption

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

drawTable

drawTableRow: row

draw one row

finishPreviousTableColumn

'HTML [info]: empty table row' infoPrintCR.

finishPreviousTableRow: final

table

=fontDescent

Usage example(s):

allow space for tables border

tableEnd

true.

tbody

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

tbodyEnd

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

td

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

th

(comment from inherited method)
intentionally left blank - to be redefined by concrete class (if required)

th_td_common

'pass1 col: ' print. currentColIndex print. ' x:' print. col x print. ' xT:' print. col xText printCR.

tr

allow space for tables leftborder

elements-text

addText: txtIn fromElement: elementArg: Transcript show:'T: '; show:needSpace; show:' '; showCR:txtIn.
drawDelayedStringsWithDelta: deltaYForDelayedText
futureDrawString: aString atX: xS y: yS yt: yT to: xE: hack: the y-offset of strings is not known, until we finish the line
(graphics may be embedded, which shift the baseLine down)
Thus, we collect the drawing calls until the line is flushed,
then call them, passing a y-offset as additional arg
possiblyAddSpaceAfter: lastAddedText: hack: if text ends with a letter,
privateDrawString2: aString atX: xS y: yS yt: yt to: xE underline: underlineArg strikeout: strikeoutArg
privateDrawString2: aString atX: xS y: yS yt: yt to: xE underline: underlineArg strikeout: strikeoutArg spanStyle: spanStyleArg
privateDrawString: aString atX: xS y: yS to: xE

formatting

flushAnchorColors: anchors notNil ifTrue:[
format: docAnchor for: aGC resolver: aResolver style: aStyle: loadedAppletClasses := nil.
process: aDocumentAnchor: skip upto applet end
reformatDocument: destination width == docWidth ifTrue:[

helpers

atLeft
atOrLeftOfLeft
atTop
break: yText is nonNil, if there was an image or widget; we have to shift the collected text then
conditionalBreak: break line if not already at the beginning
conditionalEmpty: add vertical space, but only if there is not already some
conditionalHalfEmpty: add vertical space, but only if there is not already some
currentElementHasHREF
do_needAndNewPage: handle any NEWPAGE and NEED= attributes of the current element,
put only if painting to paper (i.e. ignore if displaying)
do_starOfficeStyleBefore: handle
STYLE='page-break-before: always'
empty
empty: height
getFontsFor: aGC
halfEmpty
handlePendingSpaceNeed
header: index font: aFont space: space: don't break for headers within a list
headerEnd: self empty.
initialHeaderNumbers
needVerticalSpace: nVerticalPixel
relativeValueFrom: aString with: aNumericValue

initialization & release

initialize: (comment from inherited method)
just to ignore initialize to objects which do not need it
release: sent from docView, to release stuff
terminateMetaCommands: sent from docView, to release stuff
whenAboutToRender: tag call: aCallbackBlock: register a block to e invoked on the element to be draw.
This allows for just-in-time manipulation of eg. anchor colors.
This has been added especially for the help wizard, which wants to draw
invalid anchors (refs) in red.

meta commands

processMetaCommands: Transcript showCR:metaCmd , ' -> ' , metaArg.
refreshDocument: url

private

addSyncPoint
clearLastTextX: lastTextX is only used for PS-printing:
it remembers where the previous text ended,
in order to optimize the output (no new coordinates needed between words).
ClearlastTextX forgets any remembered position, so that the next textOut
will generate a drawString with coordinates.
displayImagesOn: destinationDevice usingPlayers: players: removeLast.
forkImageSequencePlayerFor: entry
handleColorAttribute: font and th/td elements can also specify bgColor, color etc.
handleColorChange
playImageSequence: entry: get device images first ..
rememberLastTextX: lastTextX is only used for PS-printing:
it remembers where the previous text ended,
in order to optimize the output (no new coordinates needed between words).
ClearlastTextX forgets any remembered position, so that the next textOut
will generate a drawString with coordinates.
resyncFrom: syncPoint: fetch the state found there
saveExcursion: aBlock: save the current state, perform aBlock and restore the state afterwards
saveExcursionFrom: firstElement while: testBlock: remember the current state, process elements starting with firstElement,
while testBlock returns true, finally restore the state
setupInitialState: setup some initial state, such as margins, indents,
colors, fonts etc.
startImageDisplayProcess: handle two queues in the background; the first
contains images which are to be loaded (i.e. which are
contained in the current document) and have to be
rendered for the device.
The second contains those which are to be displayed.
The displayList is always served first.
syncPoint: save my state in a sync point

queries

anchorAt: aPoint: given a (click-) point, search for and return the corresponding
anchorElement. Return nil, if there is none
elementAt: aPoint: given a (click-) point, search for and return the corresponding
element. Return nil, if there is none
elementAt: aPoint type: typeOrNil: given a (click-) point, search for and return the corresponding
element. Return nil, if there is none
height
imageAt: aPoint: given a (click-) point, search for and return the corresponding
imageElement. Return nil, if there is none
positionOfAnchor: aLocalAnchor
width

style changes

currentStyle
defaultStyle
getFontParameters: extra spacing.
normalStyle
popStyle: should not happen
pushStyle
setBGColor: aColor
setColor: aColor
setFont: aFont: self halt.
setStyle: aStyle
setUnderlineColor: aColor

widget-actions

buttonWidgetPressed: aWidgetElement: "/ pass it to the script object - if any.
formResetted: aFormElement from: aWidgetElement: reset forms contents to their original values
formSubmitted: aFormElement from: aWidgetElement: submit-button may still have an onClick... (nil if submitted via RETURN)
mouseOverAnchor: anElement: pass it to the script object - if any.

widgets

createWidgetFor: element inForm: aForm: widget backgroundColor:(destination viewBackground).
destroyWidgets
fixupForm: aForm: fixup the form: if there is a single inputField,
hideAllWidgets: hide any widget
hideWidgets: hide any widget which became invisible
prescanForm: aForm atIndex: startIndex: prescan a form, for its widgets max height.
a kludge - we need the form elements' heights BEFORE
formatting (since the text-elements have no origin knowledge,
which could be backpatched (also, we needed a way to break
MarkupText into multiple individual text items
showWidgets: show any widget which became visible

Private classes:

    BorderStyle
    Padding
    PainterState
    SpanStyle
    TextStyle
    WidgetQuery

ST/X 7.7.0.0; WebServer 1.702 at 20f6060372b9.unknown:8081; Thu, 21 Nov 2024 13:11:09 GMT