Mega Code Archive
Simple HTML parsing and painting
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Title: Simple HTML parsing and painting
Question: How to do simple HTML parsing and painting
Answer:
This morning a friend asked me how to do a simple HTML parsing. He wanted to implement a hint box with formatting possibilities.
So I developed a very simple procedure which draws the contents of a string to a rectangle on a canvas. It only understands the HTML tags b, i and u, and it moves to the next line when it finds a new line code. (This is not HTML conform, but in this case really useful)
The parsing itself is extremely simple, but you need to work with pointers and not with strings since they make it more difficult to get each individual character.
The following procedure is just a little example. If you need HTML editing/painting please try out WPTools.
// Draw simple HTML text to any canvas
// 3/16/2000 by Julian Ziersch, http://www.wptools.de
// Products: WPTools, WPReporter, WPForm
// wPDF: PDF Export for WPTools
procedure DrawHTML(r: TRect; aCanvas: TCanvas; const text: string);
var
p: PChar;
c: Char;
x, y, w, wc, hc: Integer;
code: string;
begin
p := PChar(text);
x := r.Left;
y := r.Top;
hc := aCanvas.TextHeight('Ag');
if p nil then
while p^ #0 do
begin
c := p^;
if c = ' begin
code := '';
inc(p);
while (p^ '') and (p^ #0) do
begin
code := code + uppercase(p^);
inc(p);
end;
if code = 'B' then
aCanvas.Font.Style :=
aCanvas.Font.Style + [fsBold]
else if code = 'I' then
aCanvas.Font.Style :=
aCanvas.Font.Style + [fsItalic]
else if code = 'U' then
aCanvas.Font.Style :=
aCanvas.Font.Style + [fsUnderline]
else if code = '/B' then
aCanvas.Font.Style :=
aCanvas.Font.Style - [fsBold]
else if code = '/I' then
aCanvas.Font.Style :=
aCanvas.Font.Style - [fsItalic]
else if code = '/U' then
aCanvas.Font.Style :=
aCanvas.Font.Style - [fsUnderline];
end
else if c = #10 then
begin
x := r.Left;
inc(y, hc);
end
else if c = #32 then
begin
wc := aCanvas.TextWidth(c);
if x + wc r.Right then
begin x := r.Left; inc(y, hc);
end;
if y + hc aCanvas.TextOut(x, y, c);
inc(x, wc);
end;
if p^#0 then inc(p);
end;
end;
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