Canvas questions to load images

Sun Sep 16 15:39:29 UTC 2012

I cannot think of why might else you would crave this knowledge. The 
documention, topic Canvas, will help understanding this code, you 
will need to if it is Canvas that you wish to use

At 01:31 AM 17/09/2012, you wrote:
>Thank you Alphonse, for the quick reply. More for the purpose of 
>understanding the code, than anything else, why do you 
>repeat  cnvs.Copy offScreenCnvs, myRect, myrect (with myrect twice)? 
>More specifically, how is this understood by e-prime? Also, I am 
>guessing I do not have to include a slideobject?
>
>
>
>On Sunday, September 16, 2012 10:59:26 AM UTC-4, alphonse wrote:
>
>-----------------------------------------------
>'Prepare stimulus offscreen
>offScreenCnvs.LoadImage stim
>
>'Define the copy area
>Dim myRect As Rect
>myRect.Left = xMargin
>myRect.Right = xMargin + 60
>myRect.Top = yMargin
>myRect.Bottom = yMargin + 60
>
>'Copy prepared stimulus to screen
>cnvs.Copy offScreenCnvs, myRect, myRect
>--------------------------------------------------------------------------
>
>At 12:39 AM 17/09/2012, you wrote:
>>I am currently running a dot probe task with visual paired stimuli 
>>(positive, negative). I have a two fold question pertaining to this task:
>>
>>1) I have about 60 images in one of my trialprocs, and was 
>>therefore advised to use the canvas option to preload images. I 
>>have had little success with using this object, particularly 
>>because I do not entirely understand the concepts of off-screen and 
>>on-screen canvas. I have managed to write a small script with help 
>>from the references guides posted on the e-prime website (as well 
>>as forums), but am stuck when it comes to the following statement:
>>
>>1.      When preparing the trial:
>>
>>
>>
>>targetCanvas.LoadImage stim
>>
>>
>>
>>Image is loaded to the top left corner. We need to define 2 Rect 
>>Objects: StimLoadRect and StimRect (see Rect object in the E-Basic 
>>Help), both the size of the images to-be-loaded, but the StimRect 
>>at the (Left,Right, Top,Bottom) coordinates where the stimulus will 
>>be displayed. When we copy the image from the offline canvas to the 
>>online canvas, we will copy from StimLoadRect to StimRect.
>>
>>
>>
>>2.      To run the stimulus:
>>
>>
>>
>>Display.WaitForVerticalBlank
>>
>>c.setAttrib "StimOnset", clock.read
>>
>>cnvs.copy targetCanvas, stimLoadRect, stimRect
>>
>>sleep(stimDuration)
>>
>>Display.WaitForVerticalBlank
>>
>>Cnvs.clear ' or something else that erases the stimulus, can be 
>>done in the following trial
>>
>>
>>
>>Bolded lines: How do I create a stimLoadRect and stimRect image, a 
>>is asked for? (I did find a script for creating a rect object, but 
>>am unsure of how to specify dimensions).
>>
>>I assume that pre-defining images and their locations, means I do 
>>not have to specify them as a SlideObject? (I am guessing I am 
>>completely wrong here - please feel free to correct me) . I would 
>>also assume that the stimDuration, must be defined as an attribute?
>>
>>
>>
>>Assuming I do not have to go through this convoluted path, I have 
>>another question. If I could pre-load using the SlideImage and 
>>ImageDisplay options, I am not sure how to specify the co-ordinates 
>>of where I want my image to be in the properties section. I know 
>>this appears elementary, but the actual size of the images are 424 
>>X 283, but when running, part of the images are cut off. When I 
>>looked at the properties of my slide object, I had set the width at 
>>25% . I assumed this was the co-ordinate location in relation to 
>>the actual screen size. Guessing that this was an error on my part, 
>>I reset the width to 100%, but that meant that when I looked at the 
>>slideobject (with the dotted grid), one image seemed to complete 
>>cover the other image. How do I fit both images, and make sure 
>>their dimensions remain the same?
>>
>>
>>I apologize for this rant. I only recently switched to e-prime from 
>>using Inquisit, and am still trying to get a hang of this software tool.
>>
>>
>>Thanks a ton for your reply,
>>
>>Corona
>>
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