function bounds=TextBounds(w,text,yPositionIsBaseline,centerTheText) % bounds=TextBounds(window, string [, yPositionIsBaseline=0][, centerTheText=0]) % % Returns the smallest enclosing rect for the drawn text, relative to the % current location. This bound is based on the actual pixels drawn, so it % incorporates effects of text smoothing, etc. "text" may be a cell array % or matrix of 1 or more strings. The strings are drawn one on top of % another, at the same initial position, before the bounds are calculated. % This returns the smallest box that will contain all the strings. The % prior contents of the scratch window are lost. Usually it should be an % offscreen window, so the user won't see it. The scratch window should be % at least twice as wide and high as the text, to cope with uncertainties % about text direction (e.g. Hebrew) and some unusual characters that % extend greatly to the left of their nominal starting point. If you only % know your nominal text size and number of characters, you might do this % to create your scratch window: % % Get the bounding box. % textSize=48; % string='Good morning.'; % yPositionIsBaseline=1; % 0 or 1 % w=Screen('OpenWindow',0,255); % woff=Screen('OpenOffscreenWindow',w,[],[0 0 2*textSize*length(string) 2*textSize]); % Screen(woff,'TextFont','Arial'); % Screen(woff,'TextSize',textSize); % t=GetSecs; % bounds=TextBounds(woff,string,yPositionIsBaseline) % fprintf('TextBounds took %.3f seconds.\n',GetSecs-t); % Screen('Close',woff); % % Show that it's correct by using the bounding box to frame the text. % x0=100; % y0=100; % Screen(w,'TextFont','Arial'); % Screen(w,'TextSize',textSize); % Screen('DrawText',w,string,x0,y0,0,255,yPositionIsBaseline); % Screen('FrameRect',w,0,InsetRect(OffsetRect(bounds,x0,y0),-1,-1)); % Screen('Flip',w); % Speak('Click to quit'); % GetClicks; % Screen('Close',w); % % The suggested window size in that call is generously large because there % aren't any guarantees from the font makers about how big the text might % be for a specified point size. Set your window's font, size, and % (perhaps) style before calling TextBounds. % % Be warned that TextBounds and TextCenteredBounds are slow (taking many % seconds) if the window is large. They use the whole window, so if the % window is 1024x1024 they process a million pixels. The two slowest calls % are Screen 'GetImage' and FIND. Their processing time is proportional to % the number of pixels in the window. So keep your window small. % % Also see Screen 'TextBounds'. % Also see TextCenteredBounds. % 9/1/98 dgp wrote it. % 3/19/00 dgp debugged it. % 11/17/02 dgp Added fix, image1(:,:,1), suggested by Keith Schneider to % support 16 and 32 bit images. % 9/16/04 dgp Suggest a pixelSize of 1. % 12/16/04 dgp Fixed handling of cell array. % 12/17/04 dgp Round x0 so bounds will always be integer. Add comment about speed. % 1/18/05 dgp Added Charles Collin's two e suggestion for textHeight. % 1/28/05 dgp Cosmetic. % 2/4/05 dgp Support both OSX and OS9. % 12/22/07 mk Significant rewrite to adapt to current PTB-3. % 12/16/15 dgp Added yPositionIsBaseline argument. % 01/10/16 mk Switch GetImage buffer from backBuffer to drawBuffer for compat with % use of onscreen window as scratch window with imaging pipeline active. % 01/6/17 dgp Added fourth argument to implement the tiny change needed for % TextCenteredBounds. This makes TextCenteredBounds a trivial wrapper that % automatically tracks improvements made to TextBounds. % 11/11/18 mk Avoid cast to char(), so it works with unicode as well on Octave and Matlab. % Problem with unicode reported by dgp. if nargin < 2 || isempty(text) error('Require at least 2 arguments. bounds=TextBounds(window, string [, yPositionIsBaseline][, centerTheText])'); end if nargin < 3 || isempty(yPositionIsBaseline) yPositionIsBaseline = 0; end if nargin < 4 centerTheText = 0; end white = 1; % Clear scratch window to background color black: Screen('FillRect',w,0); if yPositionIsBaseline % Draw text string baseline at location x,y with a wide margin from lower % left corner of screen. The left and lower margins accommodate the many % fonts with descenders, and the occasional fonts that have fancy capital % letters with flourishes that extend to the left of the starting point. screenRect=Screen('Rect',w); x0=screenRect(1)+min(2*Screen('TextSize',w),RectWidth(screenRect)/20); y0=screenRect(4)-min(2*Screen('TextSize',w),RectHeight(screenRect)/2); else % Draw text string with bounding box origin at upper left corner of screen. x0=0; y0=0; end if centerTheText x0=(screenRect(1)+screenRect(3))/2; end % We've only got one scratch window, so we compute the widths for centering % in advance, so as not to mess up the accumulation of letters for the % bounds. dx=zeros(1,length(text)); if centerTheText if iscell(text) for i=1:length(text) string=text(i); bounds=Screen('TextBounds',w,string); width=bounds(3); dx(i)=-width/2; end else for i=1:size(text,1) string=text(i,:); bounds=Screen('TextBounds',w,string); width=bounds(3); dx(i)=-width/2; end end end if iscell(text) for i=1:length(text) string=text(i); Screen('DrawText',w,string,x0+dx(i),y0,white,[],yPositionIsBaseline); end else for i=1:size(text,1) string=text(i,:); Screen('DrawText',w,string,x0+dx(i),y0,white,[],yPositionIsBaseline); end end % Read back only 1 color channel for efficiency reasons: image1=Screen('GetImage', w, [], 'drawBuffer', 0, 1); % Find all nonzero, i.e. non background, pixels: [y,x]=find(image1(:,:)); % Use coordinates relative to the origin of the DrawText command. y=y-y0; x=x-x0; % Compute their bounding rect and return it: if isempty(y) || isempty(x) bounds=[0 0 0 0]; else bounds=SetRect(min(x)-1,min(y)-1,max(x),max(y)); end return;