jDrawingView Text measurement
lazarus / 43-Android

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CC · 2017-11-02 23:30

Hi,

One important piece seem to be missing from  jDrawingView. Before
Drawing a text to place it properly it is important to know the  place
it would occupy in both direction.

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jmpessoa · 2017-11-02 23:47

Ok.

I will try implement text measurement!

Thank you!

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CC · 2017-11-03 00:33

jmpessoa

There is an other issue with DrawText: it is not anti-aliased, which
makes it unusable.

I am testing jView+jCanvas which has very similar functionality and
DrawText is anti-aliased here. So it would be better to implement Text
measurement for jCanvas if you can.

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CC · 2017-11-03 01:14

Bold fonts seem to be missing as well.

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CC · 2017-11-03 08:36

A  higher level solution would be to add horizontal end vertical 
alignment parameters to the DrawText function. If the Android API has
no published functionality for this I can help you to create it on the
pascal side.

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CC · 2017-11-05 22:57

This solution is working for me to align a text in a rectangle.

Add these to the source files:

....\lamw\java\lamwdesigner\jCanvas.java

Code: Java  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i        
public  void drawTextAligned(String text, float _left, float _top,
float _right, float _bottom, float _alignhorizontal , float
_alignvertical ) {                Rect bounds = new Rect();          
    paint.getTextBounds(text, 0, text.length(), bounds);             
 float x = _left + (_right - _left  - bounds.width()) *
_alignhorizontal;                float y = _top + (_bottom - _top  -
bounds.height()) * _alignvertical + bounds.height();               
canvas.drawText(text,x,y,paint);                        }

....\lamw\android_bridges\And_jni_Bridge.pas
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
jCanvas_drawTextAligned(env: PJNIEnv; Canv: jObject; const text:
string;  _left, _top, _right, _bottom, _alignhorizontal ,
_alignvertical: single);var  _jMethod : jMethodID = nil;  _jParams :
Array[0..6] of jValue;  cls: jClass; begin  _jParams[0].l :=
env^.NewStringUTF(env, pchar(text) );  _jParams[1].F := _left; 
_jParams[2].F := _top;  _jParams[3].F := _right;  _jParams[4].F :=
_bottom;  _jParams[5].F := _alignhorizontal;  _jParams[6].F :=
_alignvertical;  cls := env^.GetObjectClass(env, Canv);  _jMethod:=
env^.GetMethodID(env, cls, 'drawTextAligned',
'(Ljava/lang/String;FFFFFF)V'); 
env^.CallVoidMethodA(env,Canv,_jMethod,@_jParams); 
env^.DeleteLocalRef(env,_jParams[0].l);  env^.DeleteLocalRef(env,
cls);end; 
....\lamw\android_bridges\Laz_And_Controls.pas

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
jCanvas.drawTextAligned(Text: string; _left, _top, _right,  _bottom,
_alignhorizontal, _alignvertical: single);begin  if FInitialized then 
  jCanvas_drawTextAligned(FjEnv, FjObject, Text, _left, _top, _right, 
   _bottom, _alignhorizontal, _alignvertical );end; 
alignhorizontal / alignvertical
 0    : align left / top
 0.5  :to the middle
 1     :align right / bottom

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jmpessoa · 2017-11-06 00:07

Great!

I will add to git repo!

Thank you!

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jmpessoa · 2017-11-07 04:36

Done!

Added  DrawTextAligned  to  jCanvas and jDrawingView
and fixed  jDrawingView anti alias.

Note: Method signature changed to

DrawTextAligned(_text: string; _left, _top, _right, _bottom: single;
                           _alignHorizontal:  TTextAlignHorizontal;
                           _alignVertical: TTextAlignVertical);

where:
 
TTextAlignHorizontal = (thLeft, thRight, thCenter); 
TTextAlignVertical = (tvTop, tvBottom, tvCenter);

Thank you!

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CC · 2017-11-11 18:14

Thank you!