The Canvas scale does not apply to the font size, it applies to the vector shapes generated from the original font size. You simply cannot this:
p.setTextSize(fontSize * scale) result = p.measureText(...) You must instead do this: p.setTextSize(fontSize) result = scale * p.measureText(...) On Mon, Mar 5, 2012 at 12:35 AM, Kaloyan Donev <[email protected]> wrote: > Hi, > > The measure functions are in Paint. The scale functions are in Canvas. So I > can only measure text without any scale. And if I measure the width and > height of some text and want to draw a rectangle around it and want to use > the scale of canvas for zooming. On some zooms the text is a little narrower > and on some zooms it is a little wider. That is why I wrote the above > function because I supposed that if canvas have scale it apply scale on font > size and then draw the text with scaled font size. > > Please try to understand the log in the previous message. It is a little > strange that on closer scale levels the measured width is the same. > > And finally it is working as I expected on Android below 4.0. Why it is not > working on 4.0? What is the difference? > > On Sunday, March 4, 2012 10:17:30 PM UTC+2, Romain Guy (Google) wrote: >> >> Hi, >> >> This is not the proper way to measure scaled text. The font size >> defines the height of the font, not its width. There is no guarantee >> whatsoever that scaling a font size by a number S will scale the width >> of the text by the same number S. The proper way is to always call >> measureText() with the font size you are actually going to use. If you >> apply a scale factor on the Canvas, simply multiply the result of >> measureText() with the scale factor. >> >> >> On Fri, Mar 2, 2012 at 4:02 AM, Kaloyan Donev <[email protected]> wrote: >> > Hi, >> > >> > I am using a Typeface to draw text in canvas which have scale matrix. So >> > first I measure the width of text when scale is 1.0. Then I measure the >> > width of text when scale is different than 1.0. And I expect that non >> > scaled >> > width * scale will be equal to scaled width. This is true on devices >> > with >> > Android OS below 4.0, but on Android 4.0 it is not true. Here is sample >> > function that I wrote to test it. >> > >> > static void checkGoodForScale(Typeface face) >> > { >> > TextPaint p = new TextPaint(); >> > >> > p.setAntiAlias(true); >> > p.setSubpixelText(true); >> > >> > p.setTypeface(face); >> > >> > final String text = "During that discussion, we touched a bit on >> > the >> > psychological impact all of this—the earthquake"; >> > final float textSize = 22.f; >> > >> > p.setTextSize(textSize); >> > >> > float textWidth = p.measureText(text); >> > >> > float scale = 0.05f; >> > >> > while (scale < 1.509) >> > { >> > p.setTextSize(textSize * scale); >> > float scaledTextWidth = p.measureText(text); >> > >> > if (Math.abs(scaledTextWidth - textWidth*scale) > 1.5f) >> > { >> > Log.d("FontScaleTest", "Diff in scale width. 100% = " + >> > textWidth*scale + " " + >> > (int)(scale*100f) + "% = " + scaledTextWidth + >> > " diff = " + (scaledTextWidth - textWidth*scale) >> > ); >> > } >> > >> > scale += 0.01f; >> > } >> > } >> > >> > The above function didn't print any messages in log on Android below >> > 4.0. On >> > android 4.0 there is difference on each scale percent. I noticed that >> > widths >> > are separated in groups of 4-5 percents. For example for scale 45% if >> > width >> > is W it is the same for 46%, 47%, 48% and then on 49% it is different. >> > May >> > be there is some kind of cache for closer font sizes. >> > >> > Here is a part of my logcat: >> > >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 686.5115 51% = >> > 660.1074 >> > diff = -26.404053 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 699.7136 52% = >> > 720.1172 >> > diff = 20.403564 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 712.9157 53% = >> > 720.1172 >> > diff = 7.201477 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 726.11786 54% = >> > 720.1172 >> > diff = -6.0006714 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 739.32 55% = >> > 720.1172 >> > diff = -19.20282 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 752.52216 56% = >> > 780.12695 diff = 27.604797 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 765.72424 57% = >> > 780.12695 diff = 14.40271 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 792.12854 59% = >> > 780.12695 diff = -12.001587 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 805.3307 60% = >> > 780.12695 >> > diff = -25.203735 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 818.53284 61% = >> > 840.1367 >> > diff = 21.603882 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 831.7349 62% = >> > 840.1367 >> > diff = 8.401794 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 844.9371 63% = >> > 840.1367 >> > diff = -4.800354 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 858.1392 64% = >> > 840.1367 >> > diff = -18.002502 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 871.3414 65% = >> > 900.1465 >> > diff = 28.805115 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 884.5435 66% = >> > 900.1465 >> > diff = 15.602966 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 897.7456 67% = >> > 900.1465 >> > diff = 2.400879 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 910.94775 68% = >> > 900.1465 >> > diff = -10.80127 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 924.1499 69% = >> > 900.1465 >> > diff = -24.003418 >> > >> > Do you think this is bug in android or I am not using it the correct >> > way. >> > >> > I tried this with turned on and off hardware acceleration but there is >> > no >> > difference. >> > >> > Kaloyan >> > >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "Android Developers" group. >> > To post to this group, send email to [email protected] >> > To unsubscribe from this group, send email to >> > [email protected] >> > For more options, visit this group at >> > http://groups.google.com/group/android-developers?hl=en >> >> -- >> Romain Guy >> Android framework engineer >> [email protected] > > > On Sunday, March 4, 2012 10:17:30 PM UTC+2, Romain Guy (Google) wrote: >> >> Hi, >> >> This is not the proper way to measure scaled text. The font size >> defines the height of the font, not its width. There is no guarantee >> whatsoever that scaling a font size by a number S will scale the width >> of the text by the same number S. The proper way is to always call >> measureText() with the font size you are actually going to use. If you >> apply a scale factor on the Canvas, simply multiply the result of >> measureText() with the scale factor. >> >> >> On Fri, Mar 2, 2012 at 4:02 AM, Kaloyan Donev <[email protected]> wrote: >> > Hi, >> > >> > I am using a Typeface to draw text in canvas which have scale matrix. So >> > first I measure the width of text when scale is 1.0. Then I measure the >> > width of text when scale is different than 1.0. And I expect that non >> > scaled >> > width * scale will be equal to scaled width. This is true on devices >> > with >> > Android OS below 4.0, but on Android 4.0 it is not true. Here is sample >> > function that I wrote to test it. >> > >> > static void checkGoodForScale(Typeface face) >> > { >> > TextPaint p = new TextPaint(); >> > >> > p.setAntiAlias(true); >> > p.setSubpixelText(true); >> > >> > p.setTypeface(face); >> > >> > final String text = "During that discussion, we touched a bit on >> > the >> > psychological impact all of this—the earthquake"; >> > final float textSize = 22.f; >> > >> > p.setTextSize(textSize); >> > >> > float textWidth = p.measureText(text); >> > >> > float scale = 0.05f; >> > >> > while (scale < 1.509) >> > { >> > p.setTextSize(textSize * scale); >> > float scaledTextWidth = p.measureText(text); >> > >> > if (Math.abs(scaledTextWidth - textWidth*scale) > 1.5f) >> > { >> > Log.d("FontScaleTest", "Diff in scale width. 100% = " + >> > textWidth*scale + " " + >> > (int)(scale*100f) + "% = " + scaledTextWidth + >> > " diff = " + (scaledTextWidth - textWidth*scale) >> > ); >> > } >> > >> > scale += 0.01f; >> > } >> > } >> > >> > The above function didn't print any messages in log on Android below >> > 4.0. On >> > android 4.0 there is difference on each scale percent. I noticed that >> > widths >> > are separated in groups of 4-5 percents. For example for scale 45% if >> > width >> > is W it is the same for 46%, 47%, 48% and then on 49% it is different. >> > May >> > be there is some kind of cache for closer font sizes. >> > >> > Here is a part of my logcat: >> > >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 686.5115 51% = >> > 660.1074 >> > diff = -26.404053 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 699.7136 52% = >> > 720.1172 >> > diff = 20.403564 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 712.9157 53% = >> > 720.1172 >> > diff = 7.201477 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 726.11786 54% = >> > 720.1172 >> > diff = -6.0006714 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 739.32 55% = >> > 720.1172 >> > diff = -19.20282 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 752.52216 56% = >> > 780.12695 diff = 27.604797 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 765.72424 57% = >> > 780.12695 diff = 14.40271 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 792.12854 59% = >> > 780.12695 diff = -12.001587 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 805.3307 60% = >> > 780.12695 >> > diff = -25.203735 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 818.53284 61% = >> > 840.1367 >> > diff = 21.603882 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 831.7349 62% = >> > 840.1367 >> > diff = 8.401794 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 844.9371 63% = >> > 840.1367 >> > diff = -4.800354 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 858.1392 64% = >> > 840.1367 >> > diff = -18.002502 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 871.3414 65% = >> > 900.1465 >> > diff = 28.805115 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 884.5435 66% = >> > 900.1465 >> > diff = 15.602966 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 897.7456 67% = >> > 900.1465 >> > diff = 2.400879 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 910.94775 68% = >> > 900.1465 >> > diff = -10.80127 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 924.1499 69% = >> > 900.1465 >> > diff = -24.003418 >> > >> > Do you think this is bug in android or I am not using it the correct >> > way. >> > >> > I tried this with turned on and off hardware acceleration but there is >> > no >> > difference. >> > >> > Kaloyan >> > >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "Android Developers" group. >> > To post to this group, send email to [email protected] >> > To unsubscribe from this group, send email to >> > [email protected] >> > For more options, visit this group at >> > http://groups.google.com/group/android-developers?hl=en >> >> -- >> Romain Guy >> Android framework engineer >> [email protected] > > > On Sunday, March 4, 2012 10:17:30 PM UTC+2, Romain Guy (Google) wrote: >> >> Hi, >> >> This is not the proper way to measure scaled text. The font size >> defines the height of the font, not its width. There is no guarantee >> whatsoever that scaling a font size by a number S will scale the width >> of the text by the same number S. The proper way is to always call >> measureText() with the font size you are actually going to use. If you >> apply a scale factor on the Canvas, simply multiply the result of >> measureText() with the scale factor. >> >> >> On Fri, Mar 2, 2012 at 4:02 AM, Kaloyan Donev <[email protected]> wrote: >> > Hi, >> > >> > I am using a Typeface to draw text in canvas which have scale matrix. So >> > first I measure the width of text when scale is 1.0. Then I measure the >> > width of text when scale is different than 1.0. And I expect that non >> > scaled >> > width * scale will be equal to scaled width. This is true on devices >> > with >> > Android OS below 4.0, but on Android 4.0 it is not true. Here is sample >> > function that I wrote to test it. >> > >> > static void checkGoodForScale(Typeface face) >> > { >> > TextPaint p = new TextPaint(); >> > >> > p.setAntiAlias(true); >> > p.setSubpixelText(true); >> > >> > p.setTypeface(face); >> > >> > final String text = "During that discussion, we touched a bit on >> > the >> > psychological impact all of this—the earthquake"; >> > final float textSize = 22.f; >> > >> > p.setTextSize(textSize); >> > >> > float textWidth = p.measureText(text); >> > >> > float scale = 0.05f; >> > >> > while (scale < 1.509) >> > { >> > p.setTextSize(textSize * scale); >> > float scaledTextWidth = p.measureText(text); >> > >> > if (Math.abs(scaledTextWidth - textWidth*scale) > 1.5f) >> > { >> > Log.d("FontScaleTest", "Diff in scale width. 100% = " + >> > textWidth*scale + " " + >> > (int)(scale*100f) + "% = " + scaledTextWidth + >> > " diff = " + (scaledTextWidth - textWidth*scale) >> > ); >> > } >> > >> > scale += 0.01f; >> > } >> > } >> > >> > The above function didn't print any messages in log on Android below >> > 4.0. On >> > android 4.0 there is difference on each scale percent. I noticed that >> > widths >> > are separated in groups of 4-5 percents. For example for scale 45% if >> > width >> > is W it is the same for 46%, 47%, 48% and then on 49% it is different. >> > May >> > be there is some kind of cache for closer font sizes. >> > >> > Here is a part of my logcat: >> > >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 686.5115 51% = >> > 660.1074 >> > diff = -26.404053 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 699.7136 52% = >> > 720.1172 >> > diff = 20.403564 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 712.9157 53% = >> > 720.1172 >> > diff = 7.201477 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 726.11786 54% = >> > 720.1172 >> > diff = -6.0006714 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 739.32 55% = >> > 720.1172 >> > diff = -19.20282 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 752.52216 56% = >> > 780.12695 diff = 27.604797 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 765.72424 57% = >> > 780.12695 diff = 14.40271 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 792.12854 59% = >> > 780.12695 diff = -12.001587 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 805.3307 60% = >> > 780.12695 >> > diff = -25.203735 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 818.53284 61% = >> > 840.1367 >> > diff = 21.603882 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 831.7349 62% = >> > 840.1367 >> > diff = 8.401794 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 844.9371 63% = >> > 840.1367 >> > diff = -4.800354 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 858.1392 64% = >> > 840.1367 >> > diff = -18.002502 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 871.3414 65% = >> > 900.1465 >> > diff = 28.805115 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 884.5435 66% = >> > 900.1465 >> > diff = 15.602966 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 897.7456 67% = >> > 900.1465 >> > diff = 2.400879 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 910.94775 68% = >> > 900.1465 >> > diff = -10.80127 >> > D/FontScaleTest( 4408): Diff in scale width. 100% = 924.1499 69% = >> > 900.1465 >> > diff = -24.003418 >> > >> > Do you think this is bug in android or I am not using it the correct >> > way. >> > >> > I tried this with turned on and off hardware acceleration but there is >> > no >> > difference. >> > >> > Kaloyan >> > >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "Android Developers" group. >> > To post to this group, send email to [email protected] >> > To unsubscribe from this group, send email to >> > [email protected] >> > For more options, visit this group at >> > http://groups.google.com/group/android-developers?hl=en >> >> -- >> Romain Guy >> Android framework engineer >> [email protected] > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en -- Romain Guy Android framework engineer [email protected] -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
