Styjun

Generate ladder of integers using the least number of unique characters (in C++)

Anatomically Correct Carnivorous Tree

OSPF increase bandwidth with load-balancing

Why are solar panels kept tilted?

Why did the metro bus stop at each railway crossing, despite no warning indicating a train was coming?

How to disable Two-factor authentication for Apple ID?

Is this possible when it comes to the relations of P, NP, NP-Hard and NP-Complete?

do we have C++20 ranges library in gcc 9?

Should generated documentation be stored in a Git repository?

Wireless headphones interfere with Wi-Fi signal on laptop

Biology of a Firestarter

Formal Definition of Dot Product

Smooth function that vanishes only on unit cube

Find the unknown area, x

About matrices whose row and column sums are 0

Will a coyote attack my dog on a leash while I'm on a hiking trail?

Where to find every-day healthy food near Heathrow Airport?

A case where Bishop for knight isn't a good trade

Set a Field Equivalent in Microsoft Flow

How might a landlocked lake become a complete ecosystem?

Is 95% of what you read in the financial press “either wrong or irrelevant?”

Do I need to say “o’clock”?

Meaning of "work with shame"

How to describe a building set which is like LEGO without using the "LEGO" word?

FMX.Graphics.TCanvas.DrawEllipse doesn't work on Android

Problems running a 32-bit Delphi app on a 64-bit Windows platformHow does Delphi XE2 Firemonkey's Align property set to alScale affect the coordinate system?How to install a Delphi XE5 application permanently on a MacDelphi XE5 - TPaintBox scrolls too slow under TListBox on machines with AndroidDelphi FireMonkey Canvas performance issuesFiremonkey XE6:How to use the full resolution on my adroiddevice?dccosx Fatal ErrorDelphi 10 Seattle strange Memo behaviour on Android 6Delphi Rtti with Ios 64 BitsDelphi android app TEdit access violation

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty height:90px;width:728px;box-sizing:border-box;

1

I'm making simple drawing application with FireMonkey and Delphi. All it really does is drawing lines and ellipses. This is the code:

Image1.Bitmap.Canvas.BeginScene;
with Form1 do begin
for i := 0 to 360 do
 if (i mod 15)=0 then
 begin
 p1 := TPointF.Create(PX, PY);
 p2 := TPointF.Create(Round(PX+200*sin(i*pi/180)), Round(PY+200*cos(i*pi/180)));
 Image1.Bitmap.Canvas.DrawLine(p1, p2, 100);
 end;

for i := 0 to 200 do
 if (i mod 20)=0 then
 begin
 prst1 := TRectF.Create(PX+i,PY+i,PX-i,PY-i);
 Image1.Bitmap.Canvas.DrawEllipse(prst1, 100);
 end;
 Image1.Bitmap.Canvas.EndScene;
 end;

This code works perfectly when I compile it under Win32 or Win64. But when I try to compile it and run on an Android device, only lines show up, and ellipses are just missing. Does anyone have an idea why is that happening?

Thank you in advance for your help!

delphi firemonkey rad-studio

share|improve this question

asked Mar 23 at 13:45

brechobrecho

93

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Drawing inside an image control isn't really the proper way to draw on the screen. Try drawing directly onto the form canvas from within the form's OnPaint event handler.
  
  – Jerry Dodge
  Mar 23 at 14:29
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Please always provide details like variable initialization and types. E.g. What value do PX and PY have at entry? What if they happen to be 123456? What is the context of the code? Event handler? Your defined method? What are the brush and stroke propertiy values? Bonus question: What is the opacity value for a fully opaque line?
  
  – Tom Brunberg
  Mar 23 at 15:49
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @TomBrunberg Sorry for that. Both PX and PY are 200, and TImage is 400x400 so they really just represent the centre of the TImage. The code is under ButtonClick procedure - I just want to draw radar-like surface on the image. Then I'm drawing trajectories on it. I just have stroke and color property values, they are 3 for stroke and TAlphaColors.Black for color. Opacity value in Object Inspector for TImage is 1 (if this is what you are asking about).
  
  – brecho
  Mar 23 at 15:57
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I'm just having problem with understanding why the same FireMonkey code works under Win32 but doesn't work under Android. I'm pretty new to Delphi and I believed that the same code will work identically under both of them. Embarcadero wiki isn't really that helpful for me with my limited knowledge. Will using TPaintBox will be better than TImage in my situation when I want to draw multiple trajectories on it (so editing it in loop that works for about 1000steps)?
  
  – brecho
  Mar 23 at 16:11
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for responding to my comment, but please add that info to your question, here in the comments it is so easily overlooked. My q regarding opacity stems from your line: Image1.Bitmap.Canvas.DrawLine(p1, p2, 100);. The third parameter is the opacity, 0..1.0 acc docs, but ok, anything above 1.0 is considered 1.0.
  
  – Tom Brunberg
  Mar 23 at 17:25
  

  
  
  
  

add a comment | 

1

I'm making simple drawing application with FireMonkey and Delphi. All it really does is drawing lines and ellipses. This is the code:

Image1.Bitmap.Canvas.BeginScene;
with Form1 do begin
for i := 0 to 360 do
 if (i mod 15)=0 then
 begin
 p1 := TPointF.Create(PX, PY);
 p2 := TPointF.Create(Round(PX+200*sin(i*pi/180)), Round(PY+200*cos(i*pi/180)));
 Image1.Bitmap.Canvas.DrawLine(p1, p2, 100);
 end;

for i := 0 to 200 do
 if (i mod 20)=0 then
 begin
 prst1 := TRectF.Create(PX+i,PY+i,PX-i,PY-i);
 Image1.Bitmap.Canvas.DrawEllipse(prst1, 100);
 end;
 Image1.Bitmap.Canvas.EndScene;
 end;

This code works perfectly when I compile it under Win32 or Win64. But when I try to compile it and run on an Android device, only lines show up, and ellipses are just missing. Does anyone have an idea why is that happening?

Thank you in advance for your help!

delphi firemonkey rad-studio

share|improve this question

asked Mar 23 at 13:45

brechobrecho

93

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Drawing inside an image control isn't really the proper way to draw on the screen. Try drawing directly onto the form canvas from within the form's OnPaint event handler.
  
  – Jerry Dodge
  Mar 23 at 14:29
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Please always provide details like variable initialization and types. E.g. What value do PX and PY have at entry? What if they happen to be 123456? What is the context of the code? Event handler? Your defined method? What are the brush and stroke propertiy values? Bonus question: What is the opacity value for a fully opaque line?
  
  – Tom Brunberg
  Mar 23 at 15:49
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @TomBrunberg Sorry for that. Both PX and PY are 200, and TImage is 400x400 so they really just represent the centre of the TImage. The code is under ButtonClick procedure - I just want to draw radar-like surface on the image. Then I'm drawing trajectories on it. I just have stroke and color property values, they are 3 for stroke and TAlphaColors.Black for color. Opacity value in Object Inspector for TImage is 1 (if this is what you are asking about).
  
  – brecho
  Mar 23 at 15:57
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I'm just having problem with understanding why the same FireMonkey code works under Win32 but doesn't work under Android. I'm pretty new to Delphi and I believed that the same code will work identically under both of them. Embarcadero wiki isn't really that helpful for me with my limited knowledge. Will using TPaintBox will be better than TImage in my situation when I want to draw multiple trajectories on it (so editing it in loop that works for about 1000steps)?
  
  – brecho
  Mar 23 at 16:11
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for responding to my comment, but please add that info to your question, here in the comments it is so easily overlooked. My q regarding opacity stems from your line: Image1.Bitmap.Canvas.DrawLine(p1, p2, 100);. The third parameter is the opacity, 0..1.0 acc docs, but ok, anything above 1.0 is considered 1.0.
  
  – Tom Brunberg
  Mar 23 at 17:25
  

  
  
  
  

add a comment | 

I'm making simple drawing application with FireMonkey and Delphi. All it really does is drawing lines and ellipses. This is the code:

Image1.Bitmap.Canvas.BeginScene;
with Form1 do begin
for i := 0 to 360 do
 if (i mod 15)=0 then
 begin
 p1 := TPointF.Create(PX, PY);
 p2 := TPointF.Create(Round(PX+200*sin(i*pi/180)), Round(PY+200*cos(i*pi/180)));
 Image1.Bitmap.Canvas.DrawLine(p1, p2, 100);
 end;

for i := 0 to 200 do
 if (i mod 20)=0 then
 begin
 prst1 := TRectF.Create(PX+i,PY+i,PX-i,PY-i);
 Image1.Bitmap.Canvas.DrawEllipse(prst1, 100);
 end;
 Image1.Bitmap.Canvas.EndScene;
 end;

This code works perfectly when I compile it under Win32 or Win64. But when I try to compile it and run on an Android device, only lines show up, and ellipses are just missing. Does anyone have an idea why is that happening?

Thank you in advance for your help!

delphi firemonkey rad-studio

share|improve this question

asked Mar 23 at 13:45

brechobrecho

93

Image1.Bitmap.Canvas.BeginScene;
with Form1 do begin
for i := 0 to 360 do
 if (i mod 15)=0 then
 begin
 p1 := TPointF.Create(PX, PY);
 p2 := TPointF.Create(Round(PX+200*sin(i*pi/180)), Round(PY+200*cos(i*pi/180)));
 Image1.Bitmap.Canvas.DrawLine(p1, p2, 100);
 end;

for i := 0 to 200 do
 if (i mod 20)=0 then
 begin
 prst1 := TRectF.Create(PX+i,PY+i,PX-i,PY-i);
 Image1.Bitmap.Canvas.DrawEllipse(prst1, 100);
 end;
 Image1.Bitmap.Canvas.EndScene;
 end;

share|improve this question

asked Mar 23 at 13:45

brechobrecho

93

share|improve this question

asked Mar 23 at 13:45

brechobrecho

93

asked Mar 23 at 13:45

brechobrecho

93

asked Mar 23 at 13:45

brechobrecho

93

1 Answer
1

active

oldest

votes

1

You can draw on the Form.Canvas in the OnPaint event handler. Here is an example:

procedure TForm1.FormPaint(Sender: TObject; Canvas: TCanvas;
 const ARect: TRectF);
begin
 with Canvas do begin
 BeginUpdate;
 try
 Stroke.Kind := TBrushKind.Solid;
 Stroke.Thickness := 2.0;
 DrawEllipse(ARect,1);
 DrawLine(PointF(ARect.Left,ARect.Height / 2), PointF(ARect.right,ARect.Height / 2), 1);
 DrawLine(PointF(ARect.Left+(ARect.Width / 2),ARect.Height), PointF(ARect.Left+(ARect.Width / 2),0), 1);
 finally
 EndUpdate;
 end;
 end;
end;

share|improve this answer

edited Mar 24 at 21:56

Jerry Dodge

15.5k22112269

answered Mar 23 at 16:37

nolaspeakernolaspeaker

1,1191329

add a comment | 

Your Answer

StackExchange.ifUsing("editor", function ()
StackExchange.using("externalEditor", function ()
StackExchange.using("snippets", function ()
StackExchange.snippets.init();
);
);
, "code-snippets");

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "1"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);



);

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f55314349%2ffmx-graphics-tcanvas-drawellipse-doesnt-work-on-android%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

1

You can draw on the Form.Canvas in the OnPaint event handler. Here is an example:

procedure TForm1.FormPaint(Sender: TObject; Canvas: TCanvas;
 const ARect: TRectF);
begin
 with Canvas do begin
 BeginUpdate;
 try
 Stroke.Kind := TBrushKind.Solid;
 Stroke.Thickness := 2.0;
 DrawEllipse(ARect,1);
 DrawLine(PointF(ARect.Left,ARect.Height / 2), PointF(ARect.right,ARect.Height / 2), 1);
 DrawLine(PointF(ARect.Left+(ARect.Width / 2),ARect.Height), PointF(ARect.Left+(ARect.Width / 2),0), 1);
 finally
 EndUpdate;
 end;
 end;
end;

share|improve this answer

edited Mar 24 at 21:56

Jerry Dodge

15.5k22112269

answered Mar 23 at 16:37

nolaspeakernolaspeaker

1,1191329

add a comment | 

1

You can draw on the Form.Canvas in the OnPaint event handler. Here is an example:

procedure TForm1.FormPaint(Sender: TObject; Canvas: TCanvas;
 const ARect: TRectF);
begin
 with Canvas do begin
 BeginUpdate;
 try
 Stroke.Kind := TBrushKind.Solid;
 Stroke.Thickness := 2.0;
 DrawEllipse(ARect,1);
 DrawLine(PointF(ARect.Left,ARect.Height / 2), PointF(ARect.right,ARect.Height / 2), 1);
 DrawLine(PointF(ARect.Left+(ARect.Width / 2),ARect.Height), PointF(ARect.Left+(ARect.Width / 2),0), 1);
 finally
 EndUpdate;
 end;
 end;
end;

share|improve this answer

edited Mar 24 at 21:56

Jerry Dodge

15.5k22112269

answered Mar 23 at 16:37

nolaspeakernolaspeaker

1,1191329

add a comment | 

You can draw on the Form.Canvas in the OnPaint event handler. Here is an example:

procedure TForm1.FormPaint(Sender: TObject; Canvas: TCanvas;
 const ARect: TRectF);
begin
 with Canvas do begin
 BeginUpdate;
 try
 Stroke.Kind := TBrushKind.Solid;
 Stroke.Thickness := 2.0;
 DrawEllipse(ARect,1);
 DrawLine(PointF(ARect.Left,ARect.Height / 2), PointF(ARect.right,ARect.Height / 2), 1);
 DrawLine(PointF(ARect.Left+(ARect.Width / 2),ARect.Height), PointF(ARect.Left+(ARect.Width / 2),0), 1);
 finally
 EndUpdate;
 end;
 end;
end;

share|improve this answer

edited Mar 24 at 21:56

Jerry Dodge

15.5k22112269

answered Mar 23 at 16:37

nolaspeakernolaspeaker

1,1191329

procedure TForm1.FormPaint(Sender: TObject; Canvas: TCanvas;
 const ARect: TRectF);
begin
 with Canvas do begin
 BeginUpdate;
 try
 Stroke.Kind := TBrushKind.Solid;
 Stroke.Thickness := 2.0;
 DrawEllipse(ARect,1);
 DrawLine(PointF(ARect.Left,ARect.Height / 2), PointF(ARect.right,ARect.Height / 2), 1);
 DrawLine(PointF(ARect.Left+(ARect.Width / 2),ARect.Height), PointF(ARect.Left+(ARect.Width / 2),0), 1);
 finally
 EndUpdate;
 end;
 end;
end;

share|improve this answer

edited Mar 24 at 21:56

Jerry Dodge

15.5k22112269

answered Mar 23 at 16:37

nolaspeakernolaspeaker

1,1191329

edited Mar 24 at 21:56

Jerry Dodge

15.5k22112269

edited Mar 24 at 21:56

Jerry Dodge

15.5k22112269

answered Mar 23 at 16:37

nolaspeakernolaspeaker

1,1191329

answered Mar 23 at 16:37

nolaspeakernolaspeaker

1,1191329